Quiz about Chemistry in Class 10

Question 1

Answer the following questions with respect to the solutions marked A and B having pH values 4 and 10 respectively.  Which one of the two solutions will show acidic nature?

Accepted Answer

NA

Question 2

Answer the following questions in one word or one sentence  What is the nature of Na_(2)CO_(3) in solution?

Accepted Answer

NA

Question 3

Answer the following questions in one word or one sentence  What is the nature of aqueous solution of ammonium chloride acidic or basic?

Accepted Answer

NA

Question 4

Answer the following questions in one word or one sentence  What is the common name of sodium hydroxide?

Accepted Answer

NA

Question 5

Answer the following questions in one word or one sentence  What is the formula of blue vitriol?

Accepted Answer

NA

Question 6

Answer the following questions in one word or one sentence  What is 10H_(2)O in Na_(2)CO_(3)*10H_(2)O?

Accepted Answer

NA

Question 7

Answer the following questions [for an element having atomic number 17 ]  (a) Name the element.  (b) In which period will you find this element ?  (c) To which group of the periodic table does this element belong?  (d) State the electronic configuration of the element.

Accepted Answer

NA

Question 8

Answer the following questions about eletroplating copper ware with silver . What ions must be present in the electrolyte ?

Accepted Answer

NA

Question 9

Answer questions on the basis of your understanding of the following paragraph and the related studies concepts.  The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigationmunicipal water supply and the generation of 1000 MW of hydro electricity.  The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the Anti Tehri Dam Movement from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 100000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. What happens when water great heights is made to fall on blades of turbine?

Accepted Answer

NA

Question 10

Answer questions on the basis of your understanding of the following paragraph and the related studies concepts.  The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigationmunicipal water supply and the generation of 1000 MW of hydro electricity.  The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the Anti Tehri Dam Movement from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 100000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. Mention two disadvantages of constructing Tehri Dam.

Accepted Answer

NA

Question 11

Answer questions on the basis of your understanding of the following paragraph and the related studies concepts.  The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigationmunicipal water supply and the generation of 1000 MW of hydro electricity.  The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the Anti Tehri Dam Movement from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 100000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. How is hydropower harnessed?

Accepted Answer

NA

Question 12

Answer questions on the basis of your understanding of the following paragraph and the related studies concepts.  The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigationmunicipal water supply and the generation of 1000 MW of hydro electricity.  The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the Anti Tehri Dam Movement from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 100000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. Define 1 MW.

Accepted Answer

NA

Question 13

Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10 so there is a net positive charge giving us a sodium cation Na^+ . On the other hand chlorine provides us a negative ion Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds. Give two properties of ionic compounds.

Accepted Answer

NA

Question 14

Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10 so there is a net positive charge giving us a sodium cation Na^+ . On the other hand chlorine provides us a negative ion Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds.  Write the electronic configuration of fluorine.

Accepted Answer

NA

Question 15

Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10 so there is a net positive charge giving us a sodium cation Na^+ . On the other hand chlorine provides us a negative ion Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds. Show the formation of bond between Na and F.

Accepted Answer

NA

Question 16

Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10 so there is a net positive charge giving us a sodium cation Na^+ . On the other hand chlorine provides us a negative ion Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds.  Write the electronic configuration of sodium.

Accepted Answer

NA

Question 17

Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs. Name some household articles which make use of the malleability and ductility of metals.

Accepted Answer

NA

Question 18

Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs.  Name the property that is associated with the beating of metals into thin sheets.

Accepted Answer

NA

Question 19

Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs. Other than gold and silver name two metals that are efficiently malleable and ductile.

Accepted Answer

NA

Question 20

Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs.  You have got a piece of gold that weight 200 mg. What is the maximum length of wire approximately that you can obtain from it ?

Accepted Answer

NA

Question 21

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle we have silicon which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table a zig-zag line separates metals from non-metals. The borderline elements - boron silicon germanium arsenic antimony tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals.  (d) Give some examples of metalloids.

Accepted Answer

NA

Question 22

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle we have silicon which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table a zig-zag line separates metals from non-metals. The borderline elements - boron silicon germanium arsenic antimony tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals.  (c) What are semi-metals or metalloids ?

Accepted Answer

NA

Question 23

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle we have silicon which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table a zig-zag line separates metals from non-metals. The borderline elements - boron silicon germanium arsenic antimony tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals. (b) Why does the atomic size increase when we move down the group ?

Accepted Answer

NA

Question 24

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts.  The Modern Periodic Table has 18 vertical columns known as groups and 7 horizontal rows known as periods. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e . 1. Similarly you will find that the elements present in any one group have the same number of valence electrons. For example elements fluorine (F) and chlorine (Cl) belong to Group 17 and contain seven electrons in their outermost shells. Hence we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (d) Which position would you give to the element hydrogen ?

Accepted Answer

NA

Question 25

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle we have silicon which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table a zig-zag line separates metals from non-metals. The borderline elements - boron silicon germanium arsenic antimony tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals.  (a) Arrange the following elements in increasing order of atomic size  oxygen tellurium sulphur selenium.

Accepted Answer

NA

Question 26

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts.  The Modern Periodic Table has 18 vertical columns known as groups and 7 horizontal rows known as periods. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e . 1. Similarly you will find that the elements present in any one group have the same number of valence electrons. For example elements fluorine (F) and chlorine (Cl) belong to Group 17 and contain seven electrons in their outermost shells. Hence we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (c) Name the first element in Group 2 and the atomic number of this element.

Accepted Answer

NA

Question 27

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts.  The Modern Periodic Table has 18 vertical columns known as groups and 7 horizontal rows known as periods. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e . 1. Similarly you will find that the elements present in any one group have the same number of valence electrons. For example elements fluorine (F) and chlorine (Cl) belong to Group 17 and contain seven electrons in their outermost shells. Hence we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (b) What is the electronic configuration of the second element in Group 17 ?

Accepted Answer

NA

Question 28

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. In 1913 Henry Moseley showed that the atomic number (symbolised as Z) of an element is a more fundamental property than its atomic mass. Accordingly Mendeleevs Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows  Properties of elements are a periodic function of their atomic number. Let us recall that the atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements when arranged in order of increasing atomic number lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number.  (d) What are the advantages of Periodic Table based on Moseley concept ?

Accepted Answer

NA

Question 29

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. In 1913 Henry Moseley showed that the atomic number (symbolised as Z) of an element is a more fundamental property than its atomic mass. Accordingly Mendeleevs Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows  Properties of elements are a periodic function of their atomic number. Let us recall that the atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements when arranged in order of increasing atomic number lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number.  (b) What is Modern Periodic Law ?

Accepted Answer

NA

Question 30

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts.  The Modern Periodic Table has 18 vertical columns known as groups and 7 horizontal rows known as periods. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e . 1. Similarly you will find that the elements present in any one group have the same number of valence electrons. For example elements fluorine (F) and chlorine (Cl) belong to Group 17 and contain seven electrons in their outermost shells. Hence we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (a) What names are given to the horizontal rows and vertical columns in the Periodic Table ?

Accepted Answer

NA

Question 31

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. In 1913 Henry Moseley showed that the atomic number (symbolised as Z) of an element is a more fundamental property than its atomic mass. Accordingly Mendeleevs Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows  Properties of elements are a periodic function of their atomic number. Let us recall that the atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements when arranged in order of increasing atomic number lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number.  (c) Differentiate between atomic weight and atomic number.

Accepted Answer

NA

Question 32

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. In 1913 Henry Moseley showed that the atomic number (symbolised as Z) of an element is a more fundamental property than its atomic mass. Accordingly Mendeleevs Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows  Properties of elements are a periodic function of their atomic number. Let us recall that the atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements when arranged in order of increasing atomic number lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number.  (a) Name the principle on which Mendeleevs Periodic Table was based.

Accepted Answer

NA

Question 33

Answer question numbers (a)-(d) on the basis of your understanding of the following paragraph and related studied concepts.  Carbon has the unique ability to form bonds with other atoms of carbon giving rise to large molecules. This property is called catenation. These compounds may have long chains of carbon branched chains of carbon or even carbon atoms arranged in rings. Since carbon has a valency of four it is capable of bonding with four other atoms of carbon or atoms of some monovalent element. The bond that carbon forms with most other elements are very strong making them exceptionally stable. The reason for the formation of strong bonds by carbon is its small size.  (b) Draw the structure of a cyclic compound of carbon having six carbons and twelve hydrogens.

Accepted Answer

NA

Question 34

Answer question numbers (a)-(d) on the basis of your understanding of the following paragraph and related studied concepts.  Carbon has the unique ability to form bonds with other atoms of carbon giving rise to large molecules. This property is called catenation. These compounds may have long chains of carbon branched chains of carbon or even carbon atoms arranged in rings. Since carbon has a valency of four it is capable of bonding with four other atoms of carbon or atoms of some monovalent element. The bond that carbon forms with most other elements are very strong making them exceptionally stable. The reason for the formation of strong bonds by carbon is its small size.  (d) How does small size of carbon help in forming stable bonds with other atoms ?

Accepted Answer

NA

Question 35

Answer question numbers (a)-(d) on the basis of your understanding of the following paragraph and related studied concepts.  Carbon has the unique ability to form bonds with other atoms of carbon giving rise to large molecules. This property is called catenation. These compounds may have long chains of carbon branched chains of carbon or even carbon atoms arranged in rings. Since carbon has a valency of four it is capable of bonding with four other atoms of carbon or atoms of some monovalent element. The bond that carbon forms with most other elements are very strong making them exceptionally stable. The reason for the formation of strong bonds by carbon is its small size.  (c) If only oxygen is to be bonded to carbon how many of them will be bonded to one atom of carbon ?

Accepted Answer

NA

Question 36

Answer question numbers (a)-(d) on the basis of your understanding of the following paragraph and related studied concepts.  Carbon has the unique ability to form bonds with other atoms of carbon giving rise to large molecules. This property is called catenation. These compounds may have long chains of carbon branched chains of carbon or even carbon atoms arranged in rings. Since carbon has a valency of four it is capable of bonding with four other atoms of carbon or atoms of some monovalent element. The bond that carbon forms with most other elements are very strong making them exceptionally stable. The reason for the formation of strong bonds by carbon is its small size.  (a) Name the property which enables carbon to form bonds with other atoms of carbon.

Accepted Answer

NA

Question 37

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts.  The process of dissolving an acid or a base in water is a highly exothermic one. Care must be taken while mixing concentrated nitric acid or sulphuric acid with water. The acid must always be added slowly to water with constant stirring. If water is added to a concentrated acid the heat generated may cause the mixture to splash out and cause burns. The glass container may also break due to excessive local heating. Look out for the warning sign on the can of concentrated sulphuric acid and on the bottle of sodium hydroxide pellets. Mixing an acid or base with water results in decrease in the concentration of ions (H_3O^+OH^-) per unit volume. Such a process is called dilution and the acid or the base is said to be diluted.  What is meant by dilution of an acid or a base ?

Accepted Answer

NA

Question 38

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts.  The process of dissolving an acid or a base in water is a highly exothermic one. Care must be taken while mixing concentrated nitric acid or sulphuric acid with water. The acid must always be added slowly to water with constant stirring. If water is added to a concentrated acid the heat generated may cause the mixture to splash out and cause burns. The glass container may also break due to excessive local heating. Look out for the warning sign on the can of concentrated sulphuric acid and on the bottle of sodium hydroxide pellets. Mixing an acid or base with water results in decrease in the concentration of ions (H_3O^+OH^-) per unit volume. Such a process is called dilution and the acid or the base is said to be diluted.  What will be the consequences if dilution of acid is not carried out slowly?

Accepted Answer

NA

Question 39

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts.  The process of dissolving an acid or a base in water is a highly exothermic one. Care must be taken while mixing concentrated nitric acid or sulphuric acid with water. The acid must always be added slowly to water with constant stirring. If water is added to a concentrated acid the heat generated may cause the mixture to splash out and cause burns. The glass container may also break due to excessive local heating. Look out for the warning sign on the can of concentrated sulphuric acid and on the bottle of sodium hydroxide pellets. Mixing an acid or base with water results in decrease in the concentration of ions (H_3O^+OH^-) per unit volume. Such a process is called dilution and the acid or the base is said to be diluted.  Tell whether heat is absorbed or evolved when an acid or base is dissolved in water

Accepted Answer

NA

Question 40

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts.  The process of dissolving an acid or a base in water is a highly exothermic one. Care must be taken while mixing concentrated nitric acid or sulphuric acid with water. The acid must always be added slowly to water with constant stirring. If water is added to a concentrated acid the heat generated may cause the mixture to splash out and cause burns. The glass container may also break due to excessive local heating. Look out for the warning sign on the can of concentrated sulphuric acid and on the bottle of sodium hydroxide pellets. Mixing an acid or base with water results in decrease in the concentration of ions (H_3O^+OH^-) per unit volume. Such a process is called dilution and the acid or the base is said to be diluted.  How should acids be diluted ?

Accepted Answer

NA

Question 41

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts  Tooth decay starts when the pH of the mouth is lower than 5.5. Tooth enamel made up of calcium hydroxyapatite (a crystalline form of calcium phosphate) is the hardest substance in the body. It does not dissolve in water but is corroded when the pH of the mouth is below 5.5. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. The best way to prevent this is to clean the mouth after eating food. Using toothpastes which are generally basic for cleaning the teeth can neutralise the excess acid and prevent tooth decay. Write the best way to prevent damage to the teeth.

Accepted Answer

NA

Question 42

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts  Tooth decay starts when the pH of the mouth is lower than 5.5. Tooth enamel made up of calcium hydroxyapatite (a crystalline form of calcium phosphate) is the hardest substance in the body. It does not dissolve in water but is corroded when the pH of the mouth is below 5.5. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. The best way to prevent this is to clean the mouth after eating food. Using toothpastes which are generally basic for cleaning the teeth can neutralise the excess acid and prevent tooth decay.  Which of the following should be avoided to prevent tooth decay ? Bread cucumber cakes sweets

Accepted Answer

NA

Question 43

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts  Tooth decay starts when the pH of the mouth is lower than 5.5. Tooth enamel made up of calcium hydroxyapatite (a crystalline form of calcium phosphate) is the hardest substance in the body. It does not dissolve in water but is corroded when the pH of the mouth is below 5.5. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. The best way to prevent this is to clean the mouth after eating food. Using toothpastes which are generally basic for cleaning the teeth can neutralise the excess acid and prevent tooth decay.  What should be the pH of the mouth to prevent damage to the teeth ?

Accepted Answer

NA

Question 44

Answer question numbers (a) (d) on the basis of your understanding of the following paragraph and related studied concepts.  Copper sulphate crystals which seem to be dry contain water of crystallisation. When we heat the crystals this water is removed and the salt turns white. If you moisten the crystals again with water you will find that blue colour of the crystals reappears. Water of crystallisation that is the fixed number of water molecules present in one formula unit of a salt. Five water molecules are present in one formula unit of copper sulphate. Chemical formula for hydrated copper sulphate is CusO_(4).5H_(2)O. Now you would be able to answer the question whether the molecule of Na_(2)CO_(3).10H_(2)O is wet. One other salt which possesses water of crystallisation is gypsum. It has two water molecules as water of crystallisation. It has the chemical formula CaSO_(4).2H_(2)O  What will happen if gypsum is heated to 373 K and above ?

Accepted Answer

NA

Question 45

Answer question numbers (a) (d) on the basis of your understanding of the following paragraph and related studied concepts.  Copper sulphate crystals which seem to be dry contain water of crystallisation. When we heat the crystals this water is removed and the salt turns white. If you moisten the crystals again with water you will find that blue colour of the crystals reappears. Water of crystallisation that is the fixed number of water molecules present in one formula unit of a salt. Five water molecules are present in one formula unit of copper sulphate. Chemical formula for hydrated copper sulphate is CusO_(4).5H_(2)O. Now you would be able to answer the question whether the molecule of Na_(2)CO_(3).10H_(2)O is wet. One other salt which possesses water of crystallisation is gypsum. It has two water molecules as water of crystallisation. It has the chemical formula CaSO_(4).2H_(2)O  Explain how plaster of Paris helps in keeping fractured bones in the right position

Accepted Answer

NA

Question 46

Answer question numbers (a) – (d) on the basis of your understanding of the following paragraph and related studied concepts  Tooth decay starts when the pH of the mouth is lower than 5.5. Tooth enamel made up of calcium hydroxyapatite (a crystalline form of calcium phosphate) is the hardest substance in the body. It does not dissolve in water but is corroded when the pH of the mouth is below 5.5. Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. The best way to prevent this is to clean the mouth after eating food. Using toothpastes which are generally basic for cleaning the teeth can neutralise the excess acid and prevent tooth decay.  What is the composition of the material of teeth ?

Accepted Answer

NA

Question 47

Answer question numbers (a) (d) on the basis of your understanding of the following paragraph and related studied concepts.  Copper sulphate crystals which seem to be dry contain water of crystallisation. When we heat the crystals this water is removed and the salt turns white. If you moisten the crystals again with water you will find that blue colour of the crystals reappears. Water of crystallisation that is the fixed number of water molecules present in one formula unit of a salt. Five water molecules are present in one formula unit of copper sulphate. Chemical formula for hydrated copper sulphate is CusO_(4).5H_(2)O. Now you would be able to answer the question whether the molecule of Na_(2)CO_(3).10H_(2)O is wet. One other salt which possesses water of crystallisation is gypsum. It has two water molecules as water of crystallisation. It has the chemical formula CaSO_(4).2H_(2)O  Is a molecule wet if its formula contains water molecules ?

Accepted Answer

NA

Question 48

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts.  You must have observed that iron articles are shiny when new but get coated with a reddish brown powder when left for some time. This process is commonly known as rusting of iron. Some other metals also get tarnished in this manner. Have you noticed the colour of the coating formed on copper and silver ? When a metal is attacked by substances around it such as moisture acids etc it is said to corrode and this process is called corrosion. The black coating on silver and the green coating on copper are other examples of corrosion.  Corrosion causes damage to car bodies bridges iron railing ships and to all object made of metals especially those or iron. Corrosion of iron is a serious problem. Every year an enormous amount of money is spent to replace damaged iron.  What damage is caused to national property due to the phenomenon of rusting ?

Accepted Answer

NA

Question 49

Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts.  You must have observed that iron articles are shiny when new but get coated with a reddish brown powder when left for some time. This process is commonly known as rusting of iron. Some other metals also get tarnished in this manner. Have you noticed the colour of the coating formed on copper and silver ? When a metal is attacked by substances around it such as moisture acids etc it is said to corrode and this process is called corrosion. The black coating on silver and the green coating on copper are other examples of corrosion.  Corrosion causes damage to car bodies bridges iron railing ships and to all object made of metals especially those or iron. Corrosion of iron is a serious problem. Every year an enormous amount of money is spent to replace damaged iron.  How does the rust on copper or silver look like ?

Accepted Answer

NA

Question 50

Answer question numbers (a) (d) on the basis of your understanding of the following paragraph and related studied concepts.  Copper sulphate crystals which seem to be dry contain water of crystallisation. When we heat the crystals this water is removed and the salt turns white. If you moisten the crystals again with water you will find that blue colour of the crystals reappears. Water of crystallisation that is the fixed number of water molecules present in one formula unit of a salt. Five water molecules are present in one formula unit of copper sulphate. Chemical formula for hydrated copper sulphate is CusO_(4).5H_(2)O. Now you would be able to answer the question whether the molecule of Na_(2)CO_(3).10H_(2)O is wet. One other salt which possesses water of crystallisation is gypsum. It has two water molecules as water of crystallisation. It has the chemical formula CaSO_(4).2H_(2)O  Write the names and chemical formulae of two substances that contain water of crystallisation.

Accepted Answer

NA

Explore topic-wise InterviewSolutions in .

Answer the following questions with respect to the solutions marked 'A' and 'B' having pH values 4 and 10 respectively. Which one of the two solutions will show acidic nature?

Answer the following questions in one word or one sentence: What is the nature of Na_(2)CO_(3) in solution?

Answer the following questions in one word or one sentence: What is the nature of aqueous solution of ammonium chloride, acidic or basic?

Answer the following questions in one word or one sentence: What is the common name of sodium hydroxide?

Answer the following questions in one word or one sentence: What is the formula of blue vitriol?

Answer the following questions in one word or one sentence: What is 10H_(2)O in Na_(2)CO_(3)*10H_(2)O?

Answer the following questions [for an element having atomic number 17 ] : (a) Name the element. (b) In which period will you find this element ? (c) To which group of the periodic table does this element belong? (d) State the electronic configuration of the element.

Answer the following questions about eletroplating copper ware with silver . What ions must be present in the electrolyte ?

7651.	Answer the following questions with respect to the solutions marked 'A' and 'B' having pH values 4 and 10 respectively. Which one of the two solutions will show acidic nature?
Answer» ANSWER :A

7652.	Answer the following questions in one word or one sentence: What is the nature of Na_(2)CO_(3) in solution?
Answer» SOLUTION :It is BASIC

7653.	Answer the following questions in one word or one sentence: What is the nature of aqueous solution of ammonium chloride, acidic or basic?
Answer» SOLUTION :ACIDIC DUE to HYDROLYSIS

7654.	Answer the following questions in one word or one sentence: What is the common name of sodium hydroxide?
Answer» SOLUTION :CAUSTIC SODA

7655.	Answer the following questions in one word or one sentence: What is the formula of blue vitriol?
Answer» SOLUTION :`CuSO_(4)*5H_(2)O`

7656.	Answer the following questions in one word or one sentence: What is 10H_(2)O in Na_(2)CO_(3)*10H_(2)O?
Answer» SOLUTION :TEN MOLECULES of WATER of CRYSTALLISATION

7657.	Answer the following questions [for an element having atomic number 17 ] : (a) Name the element. (b) In which period will you find this element ? (c) To which group of the periodic table does this element belong? (d) State the electronic configuration of the element.
Answer» Solution :CHLORINE (b) Third period (c ) Group 17 (d) ELECTRONIC configuration : 2, 8, 7

7658.	Answer the following questions about eletroplating copper ware with silver . What ions must be present in the electrolyte ?
Answer» SOLUTION :`AG^(+)` IONS

7659.	Answer questions on the basis of your understanding of the following paragraph and the related studies concepts. The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigation,municipal water supply and the generation of 1000 MW of hydro electricity. The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the "Anti Tehri Dam Movement" from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 1,00,000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. What happens when water great heights is made to fall on blades of turbine?
Answer» SOLUTION :Potential ENERGY of water stored in DAM is FIRST CONVERTED into kinetic energy which is then used to rotate the blades of turbine. In turn, kinetic energy of water is converted into electrical energy.

7660.	Answer questions on the basis of your understanding of the following paragraph and the related studies concepts. The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigation,municipal water supply and the generation of 1000 MW of hydro electricity. The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the "Anti Tehri Dam Movement" from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 1,00,000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. Mention two disadvantages of constructing Tehri Dam.
Answer» Solution :(i) Displacement of INHABITANTS of old Tehri TOWN and their proper SETTLEMENT. (ii) Environmental consequences of the weak ECO system of Tehri dam site.

7661.	Answer questions on the basis of your understanding of the following paragraph and the related studies concepts. The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigation,municipal water supply and the generation of 1000 MW of hydro electricity. The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the "Anti Tehri Dam Movement" from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 1,00,000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. How is hydropower harnessed?
Answer» Solution :In a hydropower GENERATOR WATER stored in a dam is ALLOWED to fall. The FLOWING water after fall is used to rotate the turbine of generator and THUS electricity is generated.

7662.	Answer questions on the basis of your understanding of the following paragraph and the related studies concepts. The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoirof capacity 4.0 km^(3) and surface area of 52 km^(2). It is used for irrigation,municipal water supply and the generation of 1000 MW of hydro electricity. The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the "Anti Tehri Dam Movement" from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 1,00,000 people from the area has led to protracted leagal battles over resettlement rights and ultimately resulted in the delayed completion of the project. Q. Define 1 MW.
Answer» SOLUTION :`1MW=10^(6)"watts"=10^(6)` JOULE per SECOND.

7663.	Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell, then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10, so there is a net positive charge giving us a sodium cation Na^+ . On the other hand, chlorine provides us a negative ion, Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds. Give two properties of ionic compounds.
Answer» SOLUTION :(i) Ionic COMPOUNDS have HIGH MELTING and BOILING points. (ii) Ionic compounds are soluble in water and insoluble in organic solvents.

7664.	Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell, then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10, so there is a net positive charge giving us a sodium cation Na^+ . On the other hand, chlorine provides us a negative ion, Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds. Write the electronic configuration of fluorine.
Answer» Solution :FLUORINE has ELECTRONIC configuration `underset(2)(K)underset(7)(L)`

7665.	Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell, then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10, so there is a net positive charge giving us a sodium cation Na^+ . On the other hand, chlorine provides us a negative ion, Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds. Show the formation of bond between Na and F.
Answer» SOLUTION : FORMATION of BOND between NA and F

7666.	Answer questionon the basis of your understanding of the followingparagraph and related studied concepts.Sodium atom has one electron in the outermost shell. If it loses the electron from its M-shell, then it L-shell now becomes the outermost shell and that has a stable octet. The nucleus of this atom still has 11 protons but the number of electrons has become 10, so there is a net positive charge giving us a sodium cation Na^+ . On the other hand, chlorine provides us a negative ion, Cl^-by gaining the electron from Na atom. In this way the octet of Cl is also completed. These two atoms have a give and-take relationship. Thus Na^+and Cl^- being oppositely charged in nature form a bond between them called ionic bond. The compounds obtained in this manner are called ionic compounds. Write the electronic configuration of sodium.
Answer» Solution :SODIUM has electronic CONFIGURATION `underset(2)(K) underset(8)(L)underset(1)( M )`

7667.	Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs. Name some household articles which make use of the malleability and ductility of metals.
Answer» SOLUTION :Kitchen UTENSILS, BUCKET and wires for drying CLOTHES.

7668.	Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs. Name the property that is associated with the beating of metals into thin sheets.
Answer» SOLUTION :MALLEABILITY

7669.	Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs. Other than gold and silver, name two metals that are efficiently malleable and ductile.
Answer» SOLUTION :COPPER and ALUMINIUM.

7670.	Answer questionon the basis of your understanding of the following paragraph and related studied concepts.You will find that some metals can be beaten into thin sheets. This property is called malleability. Gold and silver are the most malleable metals. The ability of metals to be drawn into thin wires is called ductility. Gold is the most ductile metal. You will be surprised to know that a wire of about 2 km length can be made from one gram of gold. It is because of their malleability and ductility that metals can be given different shapes according to our needs. You have got a piece of gold that weight 200 mg. What is the maximum length of wire approximately that you can obtain from it ?
Answer» SOLUTION : ONE gram gold can be drawn into 2 km LONG wire. So 200 mg or 0.2 g gold can be drawn into 400 metres long wire.

7671.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see, the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle, we have silicon, which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table, a zig-zag line separates metals from non-metals. The borderline elements - boron, silicon, germanium, arsenic, antimony, tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals. (d) Give some examples of metalloids.
Answer» SOLUTION :Boron, silicon, GERMANIUM are EXAMPLES of metalloids.

7672.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see, the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle, we have silicon, which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table, a zig-zag line separates metals from non-metals. The borderline elements - boron, silicon, germanium, arsenic, antimony, tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals. (c) What are semi-metals or metalloids ?
Answer» SOLUTION :Semi-metals or METALLOIDS have PROPERTIES between those of METAL and non-metals.

7673.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see, the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle, we have silicon, which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table, a zig-zag line separates metals from non-metals. The borderline elements - boron, silicon, germanium, arsenic, antimony, tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals. (b) Why does the atomic size increase when we move down the group ?
Answer» Solution :This is because new SHELLS are being ADDED as we MOVE down the group. This increases the distance between the outermost ELECTRONS and the nucleus.

7674.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. The Modern Periodic Table has 18 vertical columns known as 'groups' and 7 horizontal rows known as 'periods'. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e ., 1. Similarly, you will find that the elements present in any one group have the same number of valence electrons. For example, elements fluorine (F) and chlorine (Cl), belong to Group 17, and contain seven electrons in their outermost shells. Hence, we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand, the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (d) Which position would you give to the element hydrogen ?
Answer» Solution :Hydrogen can be placed in Group 1 at the TOP POSITION or in Group 17 at the top. However, it is placed at the top of Group 1.

7675.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. You will see that the atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge. As we can see, the metals like Na and Mg are towards the left-hand side of the Periodic Table while the non-metals like sulphur and chlorine are found on the right-hand side. In the middle, we have silicon, which is classified as a semi-metal or metalloid because it exhibits some properties of both metals and non-metals. In the Modern Periodic Table, a zig-zag line separates metals from non-metals. The borderline elements - boron, silicon, germanium, arsenic, antimony, tellurium and polonium - are intermediate in properties and are called metalloids or semi-metals. (a) Arrange the following elements in increasing order of atomic size : oxygen, tellurium, sulphur, selenium.
Answer» Solution :The increasing order of atomic size of the elements is : OXYGEN `LT` SULPHUR `lt` SELENIUM `lt` tellurium

7676.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. The Modern Periodic Table has 18 vertical columns known as 'groups' and 7 horizontal rows known as 'periods'. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e ., 1. Similarly, you will find that the elements present in any one group have the same number of valence electrons. For example, elements fluorine (F) and chlorine (Cl), belong to Group 17, and contain seven electrons in their outermost shells. Hence, we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand, the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (c) Name the first element in Group 2 and the atomic number of this element.
Answer» SOLUTION :The first ELEMENT in GROUP 2 is beryllium (Be) and the ATOMIC number of this element is 4.

7677.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. The Modern Periodic Table has 18 vertical columns known as 'groups' and 7 horizontal rows known as 'periods'. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e ., 1. Similarly, you will find that the elements present in any one group have the same number of valence electrons. For example, elements fluorine (F) and chlorine (Cl), belong to Group 17, and contain seven electrons in their outermost shells. Hence, we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand, the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (b) What is the electronic configuration of the second element in Group 17 ?
Answer» SOLUTION :The SECOND element of Group 17 is chlorine. Its electronic configuration is 2, 8, 7.

7678.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. In 1913, Henry Moseley showed that the atomic number (symbolised as Z) of an element is a more fundamental property than its atomic mass. Accordingly, Mendeleev's Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows : 'Properties of elements are a periodic function of their atomic number.' Let us recall that the atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements, when arranged in order of increasing atomic number, lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number. (d) What are the advantages of Periodic Table based on Moseley concept ?
Answer» Solution :MODERN Periodic Table BASED on Moseley.s observations predicts the properties of ELEMENTS more precisely than Mendeleev.s Table.

7679.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. In 1913, Henry Moseley showed that the atomic number (symbolised as Z) of an element is a more fundamental property than its atomic mass. Accordingly, Mendeleev's Periodic Law was modified and atomic number was adopted as the basis of Modern Periodic Table and the Modern Periodic Law can be stated as follows : 'Properties of elements are a periodic function of their atomic number.' Let us recall that the atomic number gives us the number of protons in the nucleus of an atom and this number increases by one in going from one element to the next. Elements, when arranged in order of increasing atomic number, lead us to the classification known as the Modern Periodic Table. Prediction of properties of elements could be made with more precision when elements were arranged on the basis of increasing atomic number. (b) What is Modern Periodic Law ?
Answer» Solution :MODERN PERIODIC Law states that PROPERTIES of elements are a periodic function of their atomic NUMBERS.

7680.	Answer question numbers (a) - (d) on the basis of your understanding of the following paragraph and related studied concepts. The Modern Periodic Table has 18 vertical columns known as 'groups' and 7 horizontal rows known as 'periods'. Let us see what decides the placing of an element in a certain group and period. Group 1 of Modern Periodic Table contains the same number of valence electrons i.e ., 1. Similarly, you will find that the elements present in any one group have the same number of valence electrons. For example, elements fluorine (F) and chlorine (Cl), belong to Group 17, and contain seven electrons in their outermost shells. Hence, we can say that groups in the Periodic Table signify an identical outer shell electronic configuration. On the other hand, the number of shells increases as we go down the group. There is an anomaly when it comes to the position of hydrogen because it can be placed either in Group 1 or Group 17 in the first period. (a) What names are given to the horizontal rows and vertical columns in the Periodic Table ?
Answer» SOLUTION :Vertical COLUMNS are CALLED the groups and the HORIZONTAL rows are called periods.