8881 + Interview Questions in Chemistry in Class 10 Page 45 InterviewSolution

2201.	Which of the following statements is correct about an aqueous solution of an acid and of a base ? (i) Higher the pH, stronger the acid (ii) Higher the pH, weaker the acid (iii) Lower the pH, stronger the base (iv) Lower the pH, weaker the base
Answer» (i) and (iii) (ii) and (iii) (i) and (IV) (ii) and (iv) Solution :ACIDIC SOLUTIONS have pH LESS than 7 and basic solutions have pH more than 7.

Discussion

2202.	When is a chemical reaction considered a double displacement reaction ? Explain giving example. State a difference between displacement and double displacement reaction .
Answer» Solution :A REACTION is considered a double displacement reaction if during the CHEMICAL reaction an EXCHANGE of IONS takes place between two ionic substances. Example: `BaCl_(2)+Na_(2)SO_(4)rarrBaSO_(4)+2NaCl` In a displacement reaction, a more reactive element displaces or removes another element from its compound . e.g. `Fe+CuSO_(4)rarrFeSO_(4)+Cu` Whereas in a double displacement reaction, the compounds REACT by exchanging their ions andfrom two new compounds.

Discussion

2203.	Which of the following will turn blue litmus solution red ? CH_(3)OH, CH_(3)COOH, CH_(3)COOCH_(3).
Answer» SOLUTION :`CH_(3)COOH` will TURN blue litmus solution red because it is acidic.

Discussion

2204.	What is precipitation reaction? Explain with suitable examples.
Answer» Solution :When two reactants react and the PRODUCT so farmed remains INSOLUBLE and settles down as a solid, it is called a precipitate. Such reactions in which a precipitate is FORMED are called PRECIPITATION reactions·. E.g, (i) When aqueous solution of sodium sulphate is mixed with the aqueous solution or barium chloride, barium sulphate comes in the form of a white precipitate. `Na_2SO_4(aq)+BaCl_2(aq)toBaSO_4(downarrow)+2NaCl(aq)` (ii) When aqueous solution of sodium chloride is mixed with the aqueous solution of silver nitrate, silver chloride comes in the form of a white precipitate. `NaCl(aq)+AgNO_3toAgCl(downarrow)+NaNO_3`

Discussion

2205.	Write the number of covalent bonds in the molecule of ethane.
Answer» Solution :There are SEVEN covalent BONDS: `H-underset(H)underset(\|)OVERSET(H)overset(\|)C-underset(H)underset(\|)overset(H)overset(\|)C-H`

Discussion

2206.	What happens when (write balanced chemical equations only) Dry chlorine gas is passed over hot iron.
Answer» SOLUTION :`2Fe+3Cl_(2)to2FeCl_(3)`

Discussion

2207.	What does the high level of total coliform count in river Ganga indicate ?
Answer» SOLUTION :The high level of total coliform count in RIVER Ganga indicates that the WATER is contaminated by DISEASE causing microorganisms (mainly sewage).

Discussion

2208.	The sum of the numbers of protons and neutrons of an atom is called its ……………… .
Answer» SOLUTION :MASS NUMBER

Discussion

2209.	What is the chemical name of quick lime ?
Answer» CALCIUM Oxide Calcium carbonate Calcium hydroxide Carbon dioxide Answer :A

Discussion

2210.	Write the IUPAC Symbol for the element having atomic number 120.
Answer» ANSWER :UBN

Discussion

2211.	Three test tubes are taken and marked as .X., .Y. and .Z.. In test tube X, iron nail is dipped in water. In test tube Y, iron nail is dipped in mixture of water and oil. In test tube Z, iron nail is added with dry CaCl_(2). In which test tube, the iron nail will rust ? Why ?
Answer» SOLUTION :The iron NAIL will RUST in TEST tube X, because it provides the essential moist conditions for rusting SINCE both moisture as well as air is present in the test tube.

Discussion

2212.	Which of the following elements would lose an electron easily?
Answer» Mg NA K Ca ANSWER :C

Discussion

2213.	You must have been seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why those sour substances are effective in cleaning the vessel.
Answer» Solution :Copperreacts with most carbondioxide in air to form copper carbonate and as a result, copper vessel loses its SHINY brown surface forming a green layer of copper carbonate. The citric acid present in the lemon or TAMARIND NEUTRALISES the basic copper carbonate and dissovles the layer. Thast is why, tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessels its characteristic luster.

Discussion

2214.	Which amongst the following has a polar covalent bond?
Answer» NACL `NH_(3)` `O_(2)` CaO ANSWER :b

Discussion

2215.	What are covalent compounds ? Why are they different from ionic compounds ? List their three characteristics.
Answer» Solution :(a) Covalent compounds are those compounds which are formed by sharing of electrons between TWO atoms/which contain covalent bonds. (B) Covalent compounds are different from ionic compounds because the ionic compounds are formed by the transfer of electrons. (c) Three characteristics of covalent compounds are : (i) Generally have low melting and boiling points. (II) Generally INSOLUBLE or LESS soluble in water but soluble in organic solvents. (iii) Do not conduct electricity.

Discussion

2216.	You have three solutions whose pH values are 3, 7 and 9 respectively. Out of the above solutions, which solution is basic?
Answer» SOLUTION :Solution C.

Discussion

2217.	Which of the following gives the correct increasing order of acid strength?
Answer» WATER `lt` acetic acid `lt` hydrochloric acid water `lt` hydrochloric acid `lt` acetic acid Acetic acid `lt` water `lt` hydrochloric acid Hydrochloric acid `lt` water `lt` acetic acid Solution :Hydrochloric acid is a MINERAL acid and ionises completely in water that, is why it is a strong aid. Acetic acid is an ORGANIC acid and ionises only partially in water, HENCE it is a weak acid. Water has some what neutral nature. THUS , the order of acidity is water `lt`acetic acid `lt` hydrochloric acid.

Discussion

2218.	You have three solutions whose pH values are 3, 7 and 9 respectively. Out of the above solutions, which solution is acidic ?
Answer» SOLUTION :Solution A.

Discussion

2219.	What is a homologous series? Explain with an example.
Answer» Solution :A homologous series is a series of CARBON compounds that have different number of carbon atomos but CONTAIN the same FUNCTIONAL group. Fot example ,Methane,ETHANE,propane,butane etc are all part of the alkane homologous series.The genral FORMULA of this series is `C_(n)H_(2n+2)` Methane:`CH_(3)CH_(4)` Propane:`CH_(3)CH_(2)CH` Butane: `CH_(3)CH_(2)CH_(2)CH_(3)` It can be noticed that there is a difference of `CH_(2)` unit between each successive compounds.

Discussion

2220.	Which coating is applied on electric wire ?
Answer» DDT PVC PTFE PAN SOLUTION :PVC

Discussion

2221.	Which metal oxides dissolve in water to form alkali? Write their balanced chemical equations.
Answer» Solution :OXIDES of active METALS like sodium and potassium dissolve in water to form alkali. For example, `Na_2O(s) + H_2O(L)to 2NaOH(aq)` ` K_2O(s) + H_2O(l)to2KOH(aq)`

Discussion

2222.	What happens when ZnCO_(3) is heated in the absence of air ? Give the relevant equation.
Answer» SOLUTION :`ZnO(s) and CO_(2) (g)` are FORMED. Chemical EQUATION: `ZnCO_(3) RARR ZnO+CO_(2)`

Discussion

2223.	When magnesium burn in air , anothercompound is formed along with magnesium oxide . Name the compound.
Answer» MAGNESIUM peroxide. Magnesium NITRITE Magnesium nitride none of the above ANSWER :C

Discussion

2224.	What are isobars ? Give example.
Answer» Solution :Atoms of DIFFERENT elements that have same atomic MASSES but different atomic numbers are CALLED ISOBARS. e.g., `""_(18)Ar^(40),""_(20)Ca^(40),`

Discussion

2225.	Which of the following conclusions could not be derived from Rutherford's is alpha- ray scattering experiment?
Answer» Most of the space in the atom is empty The RADIUS of the atom is about `10^(-10)m` while that of nucleus is `10^(15)`m Electrons MOVE in a circular PATH of fixed energy called orbits Electrons and the nucleus are held TOGETHER by electrostatic forces of attraction Answer :C

Discussion

2226.	Which among the following statement(s) is (are) true ? Exposure of silver chloride to sunlight for a long duration turns grey ddue to (i) the formation of silver by decomposition of silver shloried. (ii) sublimation of silver chloride. (iii) decomposition of chlorine gas from silver chloride. (iv) oxidation of silver chloride.
Answer» (i) only (i) and (iii) (II) and (iii) (iv) only SOLUTION :Silver chloride turns grey due to the formation of silver by DECOMPOSITION of silver chloride.

Discussion

2227.	What is homologous series ? Explain with example.
Answer» Solution :Homologous Series. It is a series or organic compound which 1. Can be REPRESENTED by same general formula. 2. Can be prepared by same method. 3. Have same (almost) chemical properties. it should be noted that on seeing the molecular formulae of different members we find that the SUCCESSIVE members differ by `-CH_(2)` unit. Similarly on seeing theirmolecular WEIGHTS we find that the successive members differ by 14 units.

Discussion

2228.	What is the common nodal plane of d_(xy) and d_(zx)
Answer» SOLUTION :(i) shape of dzx and `d_(xy)` ORBITALS (ii) orienthtion of lobes of `d_(xy)` and `d_(xz)` orbitals (iii) PLANES where probability of finding an electron is ZERO

Discussion

2229.	Transition Elements.
Answer» Solution :(i) Elements present in groups 3 to 12 in the MIDDLEOF the periodic table are CALLED transition elements. (ii) Their LAST two outermost shells are INCOMPLETE. (iii) They belong to d-block of Modem Periodic table. (iv) All these elements are solid METALS at room temperature (except Mercury and Gallium).

Discussion

2230.	Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period ?
Answer» `A,B, C` `B, C,D` `A,D, E` `B, D,E` Solution :Elements B (LI), C (N) and D (Ne) belong to the same GROUP.

Discussion

2231.	What would you observe when zinc is added to a solution of Iron (II) sulphate? Write the chemical reaction that takes place.
Answer» Solution : Zinc (Zn) is more reactive than IRON (Fe). HENCE, when it is added to iron (II) sulphate, it displaces the iron METAL. As a result, the COLOUR of the solution fades from GREEN to colourless due to formation of zinc sulphate, and the greyish black coloured iron metal gets displaced. `Zn(s) + FeSO_4(aq) to ZnSO_4(aq) + Fe(s)`

Discussion

2232.	Transition elements
Answer» Solution :The elements in which last TWO shells are INCOMPLETELY filled are CALLED Transition elements . They belong to d-block of MODEM Periodic Table.

Discussion

2233.	Which ancient systems of water harvesting can be rejuvenated? What is the major advantage of these methods?
Answer» SOLUTION :Kattar, ponds, tals, tanks, surang arms pynes and ahars are some of the ancient water HARVESTING methods. We can STORE more amount of water. This water is used for agricultural purpose and also we can generate ELECTRICITY. It provides moisture for vegetation over a wide area. It is PROTECTED from contamination of human and animal waste. It does not provide breeding grounds for mosquitoes like stagnant water collected in ponds.

Discussion

2234.	What is meant by chemical equation ? Explain its characteristics with example.
Answer» Solution :Symbolic representation of CHEMICAL reaction using symbols and formulae of the substances involved in it is called chemical equation. Characteristics : (1) Substances which are involved in the chemical reaction are known as reactants and they are written on the left side of the arrow (`to` ) sign. (2) Substances which are formed at the end of the chemical reaction are known as products and they are written on the right side of the arrow (→) sign. (3) In chemical equation, the physical states of the reactants and products are mentioned, such as (s) for SOLID, (1) for liquid, (g) for gas and (aq) for an aqueous solution. These notations (s), (1). (g) and (aq) are shown at right (just after their formula) in bracket with small letters. For example `2Na(s)+2H_(2)O(I) to 2NaOH(aq)+H_(2)(g)` (4) In chemical equation, the GASEOUS PRODUCT is represented by putting an arrow pointing upwards (`uarr`) and an insoluble product (Precipitate) is represented by putting an arrow pointing downwards (`darr`). For example (i) `C(s)+O_(2)(g) to CO_(2)(g)` or `CO_(2)(uarr)` (ii) `AgNO_(3)(aq)+NaCl(aq) to NaNO_(3)(aq) +AgCl(s)` or `AgCl(darr)` Some chemical reactions take place under specific reaction conditions such as temperature, pressure, catalyst which are shown above / below the arrow in the equation. For example `N_(2)(g)+3H_(2)(g) underset("200-300 Bar")overset(773K, [Fe])to 2NH_(3)(g)` (6) ACCORDING to the law of conservation of mass, chemical equation should be written as balanced equation. For example `2KClO_(3)(s) overset(Delta)to 2KCl(s) +3O_(2)`

Discussion

2235.	Write the number of vertical columns in the periodic table. What are these columns called?
Answer» SOLUTION :The NUMBER of VERTICAL COLUMNS in the periodic table is 18.These columns are called GROUPS.

Discussion

2236.	The simultaneus location of both the position and the velocity of an electron in motion cannot be found with desired accuary ' This was proposed by
Answer» Bohr Heisenberg Sommerfeld de Broglie Answer :B

Discussion

2237.	What is the difference between empirical formula and molecular formula ?
Answer» ANSWER :CH

Discussion

2238.	What will happen if a solution of sodium hydro carbonate is heated ? Give the equation of the reaction involved.
Answer» SOLUTION :When sodium HYDROGEN carbonate is HEATED then sodium carbonate and water is formed ALONG with the evolution of carbon dioxide GAS. `2NaHCO_3 to^(Delta) Na_2CO_3+ H_2O+CO_2`

Discussion

2239.	Which of the following is an alloy?
Answer» Brass Bronze STEEL All of the GIVEN Solution : All of the given

Discussion

2240.	Two elements with symbol X (atomic no. 16) and Y (atomic no. 12) are placed in the III period ofthe Modern Periodic Table.(i) Which amongst the two has more metallic character? (ii) Calculate the valency of each element.(iii) Element ‘Y' is smaller than 'X' in terms of atomic size. Is the statement true, justify?
Answer» Solution : (i) Y(II) 2 each (iii) False, same PERIOD but Y LIES in group 2 and X in group 16. So, as we MOVE from LEFT to rightsize decreases with increase in nuclear charge.

Discussion

2241.	What is Tyndall effect? What is its cause ? Name two phenomena observed in daily life based on Tyndall effect.
Answer» Solution :Tyndal cffect: When a beam of light is passed through a colloidal solution placed in a dark room the path of beam BECOMES illuminated when observed through a microscope placed perpcndicular to the path of light. This effect is called Tyndall effect. Causes of tyndal effeet: The size of the callidal partical is relatively larger then the SOLUTE particals OFA true solution. The collidal particles first absorb energy from the INCIDENT light and then a part of energy from their surface. Thus tyndall effect is due to scattering of light by the colloidal particals and the colloidal particles are seen to be moving as points of lights moving aginist a dark background. Daily life examples : (i) When sunlight passcs though a canopy of a dense FOREST the tiny water droplets in the mist scatter light and become visible. (ii) When a fine beam of sunlight entersa smoke filled room through a small hole the smoke particals become visible due to the scattcring of light.

Discussion

2242.	What is baking soda ? How is it prepared ? Give its important properties and uses.
Answer» Solution :Baking soda is sodium hydrogen carbonate or sodium bicarbonate. Its chemical formula is `NaHCO_3`. PREPARATION. Sodium hydrogen carbonate is prepared in the laboratory by passing carbon dioxide through a cold saturated solution of sodium carbonate. `UNDERSET("Sodium carbonate")(Na_2CO_3) + H_2O + CO_2 to underset("Sodium bicarbonate")(2NaHCO_3)` Because of its low solubility, it separates out as white crystals. It is also manufactured as a primary product in the Solvay PROCESS for the MANUFACTURE of washing soda. Properties 1. Sodium bicarbonate is white crystalline solid. 2. It is soluble in water and its aqueous solution is alkaline in nature. 3. On heating, sodium bicarbonate gets converted into sodium carbonate with the evolution of carbon dioxide gas. `underset("Sod. bicarbonate")(2NaHCO_3) overset("Heat")to Na_2CO_3 + CO_2 + H_2O` Since carbon dioxide is given off on heating, it is used as a constituent of baking powder to aerate the dough. Uses of Baking Soda 1. It is mainly used in the preparation of baking powder. Baking powder contains sodium hydrogen carbonate and an acid like tartaric acid or citric acid. 2. It is used in medicines to remove acidity of the stomach. Therefore, it is an important constituent of an ANTACID. 3. It is used in the manufacture of aerated water (soda water). 4. Sodium bicarbonate is also used in fire extinguisher.

Discussion

2243.	what is vinegar?
Answer» Solution :A 5-8% solution of ACETIC ACID in WATER is called vinegar and is used widely as a PRESERVATIVE in pickles.

Discussion

2244.	Which of the following metals forms amphoteric oxide when it reacts with oxygen?
Answer» SODIUM magnesium aluminium potassium Solution :`Al_(2)O_(3)` is an AMPHOTERIC OXIDE that reacts with both ACIDS and bases.

Discussion

2245.	What happens when ethyl alcohol is heated with excess of sulphuric acid at 170^@C
Answer» SOLUTION :`underset("ETHANOL")(C_2H_5OH) overset(H_2SO_4 , 170^@C)(to) underset("ETHANE")(C_2H_4) + underset("water")(H_2O)`

Discussion

2246.	Write the electron dot structural formula and graphic structural formula of methane
Answer» SOLUTION :

Discussion

2247.	Write the chemical equations for the following chemical reactions and name the carboniccompound obtained. (i) Reaction of acidified potassium dichromate solution with ethanol on heating. (ii) Reaction of sodium metal with ethanol. (iii) Reaction of concentrated sulphuric acid with ethanol at 443 K.
Answer» Solution :(i) Ethanol is oxidised to ethanoic acid with the help of acidified `K_(2)Cr_(2)O_(7)`. `CH_(3)CH_(2)OH +2[O]rightarrowCH_(3)COOH + H_(2)O` (ii) Ethanol reacts with SODIUM metal to form sodium ethoxide and HYDROGEN gas. `2C_(2)H_(5)OH rightarrow2C_(2)H_(5)ONa+H_(2)` (iii) Ethene is formed when ethanol is heated at 443 K with pricentrated sulphuric acid Concentrated readtion and sulphuric acid ACTS as dehydrating agent in this reactionand removes a molecule of water. `CH_(3)CH_(2)OH overset(H_(2)SO_(4))underset"443K"to CH_(2)=CH_(2)+H_(2)O`

Discussion

2248.	Which of the following substance is antacid
Answer» NaCl `Mg(OH_(2))` HCl `H_(2)SO_(4)` ANSWER :B

Discussion

2249.	Which acid is present in vinegar ?
Answer» SOLUTION :ACETIC ACID

Discussion

2250.	When both pressure and temperature of a given mass of a gas are increased by 'n' times , thevolume occupied by the same mass of the gas remains thesame. Justify withrespect to kinetic moleculartheory.
Answer» Solution :(i) CHANGE in thearrangement of molecules with increase in TEMPERATURE (II) change in thearrangement of molecules with increase in pressure (iii) comparison of THESECHANGES .

Discussion

Explore topic-wise InterviewSolutions in .

Which of the following statements is correct about an aqueous solution of an acid and of a base ? (i) Higher the pH, stronger the acid (ii) Higher the pH, weaker the acid (iii) Lower the pH, stronger the base (iv) Lower the pH, weaker the base

When is a chemical reaction considered a double displacement reaction ? Explain giving example. State a difference between displacement and double displacement reaction .

Which of the following will turn blue litmus solution red ? CH_(3)OH, CH_(3)COOH, CH_(3)COOCH_(3).

What is precipitation reaction? Explain with suitable examples.

Write the number of covalent bonds in the molecule of ethane.

What happens when (write balanced chemical equations only) Dry chlorine gas is passed over hot iron.

What does the high level of total coliform count in river Ganga indicate ?

The sum of the numbers of protons and neutrons of an atom is called its ……………… .

What is the chemical name of quick lime ?

Write the IUPAC Symbol for the element having atomic number 120.

Three test tubes are taken and marked as .X., .Y. and .Z.. In test tube X, iron nail is dipped in water. In test tube Y, iron nail is dipped in mixture of water and oil. In test tube Z, iron nail is added with dry CaCl_(2). In which test tube, the iron nail will rust ? Why ?

Which of the following elements would lose an electron easily?

You must have been seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why those sour substances are effective in cleaning the vessel.

Which amongst the following has a polar covalent bond?

What are covalent compounds ? Why are they different from ionic compounds ? List their three characteristics.

You have three solutions whose pH values are 3, 7 and 9 respectively. Out of the above solutions, which solution is basic?

Which of the following gives the correct increasing order of acid strength?

You have three solutions whose pH values are 3, 7 and 9 respectively. Out of the above solutions, which solution is acidic ?

What is a homologous series? Explain with an example.

Which coating is applied on electric wire ?

Which metal oxides dissolve in water to form alkali? Write their balanced chemical equations.

What happens when ZnCO_(3) is heated in the absence of air ? Give the relevant equation.

When magnesium burn in air , anothercompound is formed along with magnesium oxide . Name the compound.

What are isobars ? Give example.

Which of the following conclusions could not be derived from Rutherford's is alpha- ray scattering experiment?

What is homologous series ? Explain with example.

What is the common nodal plane of d_(xy) and d_(zx)

Transition Elements.

Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period ?

What would you observe when zinc is added to a solution of Iron (II) sulphate? Write the chemical reaction that takes place.

Transition elements

Which ancient systems of water harvesting can be rejuvenated? What is the major advantage of these methods?

What is meant by chemical equation ? Explain its characteristics with example.

Write the number of vertical columns in the periodic table. What are these columns called?

The simultaneus location of both the position and the velocity of an electron in motion cannot be found with desired accuary ' This was proposed by

What is the difference between empirical formula and molecular formula ?

What will happen if a solution of sodium hydro carbonate is heated ? Give the equation of the reaction involved.

Which of the following is an alloy?

What is Tyndall effect? What is its cause ? Name two phenomena observed in daily life based on Tyndall effect.

What is baking soda ? How is it prepared ? Give its important properties and uses.

what is vinegar?

Which of the following metals forms amphoteric oxide when it reacts with oxygen?

What happens when ethyl alcohol is heated with excess of sulphuric acid at 170^@C

Write the electron dot structural formula and graphic structural formula of methane

Write the chemical equations for the following chemical reactions and name the carboniccompound obtained. (i) Reaction of acidified potassium dichromate solution with ethanol on heating. (ii) Reaction of sodium metal with ethanol. (iii) Reaction of concentrated sulphuric acid with ethanol at 443 K.

Which of the following substance is antacid

Which acid is present in vinegar ?

When both pressure and temperature of a given mass of a gas are increased by 'n' times , thevolume occupied by the same mass of the gas remains thesame. Justify withrespect to kinetic moleculartheory.