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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 951. |
The arrangement of eight electrons in the outermost shell of an atom is called ______ |
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Answer» |
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| 952. |
The ............ arearranged in the empty space around the ................ of the atom . |
| Answer» SOLUTION :ELECTRONS, NUCLEUS | |
| 954. |
The antibioticPenicillin is obtained from …………………. . |
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Answer» plant |
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| 955. |
The anomalous pairs in mendeleev 's periodic table is / are __________ |
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Answer» CO,Ni `Cu,Ni,Te,I,Ar,K |
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| 956. |
The anhydrous salt which is used to test water as it changes colour when water is added to it.Sodium chloride ,Magnesium sulphate,Zinc chloride,Copper sulphate. |
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Answer» SODIUM chloride |
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| 957. |
The amount of which salt in the sea is the highest ? |
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Answer» CALCIUM fluoride |
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| 958. |
The amount of solute (H_(2)SO_(4)) and solvent present in a solution are 49 g and 90 g. respectively. If the specific gravities of the solute and solvent are 1.96 and 0.9, respectively, then calculate the molarity of the solution. |
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Answer» SOLUTION :(i) DETERMINATION of the volumes of the solute and solvent (II) calculation of total VOLUME of the solution (iii) calculation of number of moles of `H_(2)SO_(4)` (iv) calculation of molarity of solution |
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| 959. |
The age of a dead animal can be determined by using an isotone of |
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Answer» CARBON |
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| 960. |
The activation energy for the forward reaction of A+B hArr C+D is 50 kJ/mole. If the energy of the products is 10 kJ mole more than that of reactants, the activation energy for the formation of reactants from the products is |
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Answer» 60 kJ/mole |
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| 963. |
Tha mass per unit volume of substance is called density. (density = mass/volume). Arrange the following in order of increasing density-air, exhaust from chimneys, honey, water, chalk, cotton andiron. |
| Answer» Solution :Air>exhaust from CHEMNEY>COTTON>WATER>HONEY>chalk>Iron. | |
| 964. |
Th rate of diffusion is very fast in gases. Why? |
| Answer» SOLUTION :A gas diffuses into ANOTHER gas very fast because of high SPEED of the particles and a large SPACE between them. | |
| 967. |
Teena and Neena while reading books on ozone depletion came across some information which is given below. Both chlorofluorocarbons (freons) and oxides of nitrogen can catalyse the destruction of ozone in the upper layer of the atmosphere. The activation energies of the reactions which cause ozone depletion are 2.1 kJ/mole in the presence of freons and 11.9 kJ/mole in the pressure of the oxides of nitrogen. Based on the above information, Teena and Neena had an argument. According to Teena, freons are more harmful. In Neena's opinion, the oxides of nitrogen cause more harm. Can you justify who is correct ? |
| Answer» Solution :Activation ENERGY is the difference between the threshold energy of the reaction and the kinetic energy of the colliding molecules. That means it gives the energy barrier the REACTANT molecules have to cross in order to result in EFFECTIVE collisions. The reaction with less activation energy can cross the energy barrier easily, and hence, the reaction takes place at a faster rate. The reaction with high activation energy has a greater energy gradient. As a result, the reaction is COMPARATIVELY slower. In the case of the destruction of ozone in the upper layers of the atmosphere, the activation energy for the reaction catalysed by CHLOROFLUOROCARBONS is less, i.e., 2.1 kJ/mole. Hence, it takes place faster when compared to the reaction catalysed by nitric oxide which has higher activation energy of 11.9 kJ/mole. From this, it is obvious that chlorofluorocarbons are more harmful to the environment with respect to ozone depletion. | |
| 968. |
Rana was in a haste to go to attenda marriage party , but he found that his shirt was yet wet . Suggest some ways by which he may dry his shirt faster . |
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Answer» SOLUTION :The wet clothes can be dried in a number of ways. (i) By SPREADING them in air under sun so that the WATER may evaporate. (ii) By spreading them under a fan in a room. (iii) By ironing the clothes. As a result, the moisture present will escape as STEAM / vapours and the clothes will soon BECOME dry. |
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| 969. |
Take some powdered iron filings and mix it with sulphur. (i) Divide the mixture into two equal halves. (ii) Keep the first half of the mixture as it is, but best the second half of the mixture. (iii) You will geta grey brittle compound |
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Answer» Solution :Iron + Sulphur `overset(DELTA)(rarr)` Iron sulphide We cannot SEPARATE iron from iron sulphide. So, it is a compound, whereas Iron and sulphur are mixtures. We can separate it by magnetic SEPARATION method. |
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| 970. |
Take some full-cream milk in a test tube. Centrifuge it by using a centrifuging machine for two minutes. If a centrifuging machine is not available in the school, you can do this activity at home by using a milk churner, used in the kitchen. Explain how the separation of cream from milk takes place. |
| Answer» SOLUTION :Separation of CREAM from milk takes place by CENTRIFUGATION due to the difference in the DENSITIES of the particles in milk. | |
| 971. |
Take some full-cream milk in a test tube. Centrifuge it by using a centrifuging machine for two minutes. If a centrifuging machine is not available in the school, you can do this activity at home by using a milk churner, used in the kitchen. What do you observe on churning the milk ? |
| Answer» SOLUTION :On churning the milk, LIGHTER particles move UPWARD and some solid particles START settling towards the bottom of the test tube. | |
| 972. |
Take some (approximately 5 g) impure sample of copper sulphate in a china dish. Dissolve it in minimum amount of water. Filter the impurities out. Evaporate water from the copper sulphate solution so as to get a saturated solution. Cover the solution with a filter paper and leave it undisturbed at room temperature to cool slowly for a day. Do the crystals look alike? |
| Answer» SOLUTION :YES, the CRYSTALS LOOK ALIKE. | |
| 973. |
Take some (approximately 5 g) impure sample of copper sulphate in a china dish. Dissolve it in minimum amount of water. Filter the impurities out. Evaporate water from the copper sulphate solution so as to get a saturated solution. Cover the solution with a filter paper and leave it undisturbed at room temperature to cool slowly for a day. How will you separate the crystals from the liquid in the china dish ? |
| Answer» Solution :To separate the CRYSTALS from the liquid in the CHINA dish use FILTER PAPER. The crystals will get spread on the filter paper and the WATER will be absorbed by filter paper. | |
| 974. |
Take some (approximately 5 g) impure sample of copper sulphate in a china dish. Dissolve it in minimum amount of water. Filter the impurities out. Evaporate water from the copper sulphate solution so as to get a saturated solution. Cover the solution with a filter paper and leave it undisturbed at room temperature to cool slowly for a day. What do you observe in the china dish ? |
| Answer» SOLUTION :CRYSTAL of COPPER sulphate STARTS forming in the CHINA dish. | |
| 975. |
Take bottles containing sugar, starch and wheat flour. Add one tea spoon full of each one to a glass of water and stir well. Leave it aside for about ten minutes. What do you opbserve? |
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Answer» SOLUTION :(a) Sugar in water is true solution. (b) Starch in water is a COLLOIDAL solution. (C ) Wheat in water is a SUSPENSION. |
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| 976. |
Take solutions of hydrochloric acid or sulphuric acid. . Fix two nails on a cork and place the cork in a 100 ml beaker. . Connect the nails to the two terminals of a 6V battery through a bulb and a switch as shown in Figure. . Now pour some dilute HCl in the beaker and switch on the current. Repeat the activity with dilute sulphuric acid, glucose and alcohol solutions. What do you observe now? . Does the bulb glow in all cases? |
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Answer» Solution :The bulb GLOWS when the solution in the beaker is hydrochloric ACID or sulphuric acid as they ionise into `H^(+)` ions thus facilitating the flow of current. Both hydrochloric acid and sulphuric acid readily ionise to `H^(+), Cl^(-) and 2H^(+) and SO^(4-)` in solution and thus CONDUCT ELECTRICITY letting the bulb glow. Wherens glucose and ALCOHOL do not ionise and hence the bulb doesn.t glow. |
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| 977. |
Take approximately 50 mL of water each in two separate beakers. Add salt in one beaker and sugar or barium chloride in the second beaker with continuous stirring. When no more solute can be dissolved, heat the contents of the beaker to raise the temperature by about 5^(@)C. Start adding the solute again. Is the amount of salt and sugar or barium chloride, that can be dissolved in water at a given temperature, the same ? |
| Answer» SOLUTION :The SOLUTIONS of salt and sugar (or BARIUM CHLORIDE) are saturated solutions at the given temperature. | |
| 978. |
Take about 10 ml of dilute hydrochloric acid in a test tube and add a few pieces of zine. granules into it. What do you observe? Why are bubbles formed in the solution? Take a burning candle near a bubble containing hydrogen gas, the flame goes off with "Popping' sound. This confirms that metal displaces hydrogen gas from the dilute acid. |
| Answer» Solution :Bubbles are formed as ZINC reacts with HC1 to FORM ZNCL and HYDROGEN gas is released. | |
| 979. |
Take 5 g of iron filling and 5 g sulphur in a china dish. By which of the following processes will a compound be formed ? |
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Answer» On mixing both of them vigorously. |
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| 980. |
Tabulate the differences in the states of matter on the basis of (i) kinetic energy (ii) density (iii) force of attraction between particles. |
Answer» SOLUTION :
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| 981. |
Symbols of certain elements are given. Write their electronic configuration and find the period and group in which 'they are included. 13^27Al |
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Answer» ELECTRONIC CONFIGURATION 2,8,3 PERIOD - 3 Group - 13 |
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| 982. |
Symbols of certain elements are given. Write their electronic configuration and find the period and group in which 'they are included. 10^20Ne |
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Answer» ELECTRONIC CONFIGURATION 2,8 PERIOD - 2 Group - 18 |
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| 983. |
Symbols of certain elements are given. Write their electronic configuration and find the period and group in which 'they are included. 12^24Mg |
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Answer» ELECTRONIC CONFIGURATION 2,8,2 PERIOD - 3 Group -2 |
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| 984. |
Symbols of certain elements are given. Write their electronic configuration and find the period and group in which 'they are included. _6^12C |
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Answer» ELECTRONIC CONFIGURATION 2, 4 PERIOD - 2 Group-14 |
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| 985. |
Symbols of certain elements are given. Write their electronic configuration and find the period and group in which 'they are included. 17^35Cl |
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Answer» ELECTRONIC configuration 2,8,7 Period - 3 GROUP -17 |
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| 986. |
Symbols of certain elements are given write down the electronic configuration and find the period and group in which they are included. 9^19F |
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Answer» Electron CONFIGURATION - 2, 7 PERIOD - 3 Group-17 |
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| 987. |
Symbols of certain elements are given write down the electronic configuration and find the period and group in which they are included. _17^35Cl |
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Answer» ELECTRON CONFIGURATION - 2, 8, 7 Period - 3 GROUP 17 |
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| 988. |
Symbols of certain elements are given write down the electronic configuration and find the period and group in which they are included. 11^23Na |
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Answer» ELECTRON configuration 2, 8, 1 PERIOD - 3 Group -1 |
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| 989. |
Symbolically represent the following atoms using atomic number and mass number . (a) Carbon(b)Oxygen( c) Silicon(d)Beryllium |
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Answer» Solution :(a) Carbon `= ""_(12)^(6)C` (b)Oxygen `= ""_(16)^(8)O` ( c) Silicon `= " "_(28)^(14)S` (d) Beryllium `= ""_(9)^(4)Be` |
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| 990. |
Supernatant denotes the heterogenous mixture, lying above a solid residue, after crystallization precipitation,centrifugation or other process. |
| Answer» SOLUTION :Correct statement: Supernatant denotes the liquid lying above a solid residue after crystallization precipitation, CENTRIFUGATION or other process. | |
| 991. |
Summarize the rule for writing of distribution of electrons in various shell for the first eighteen elements. |
| Answer» SOLUTION :The rules for writing of the distribution of electrons in various shells for the first eighteen elements are GIVEN below.If n given number of orbit or energy level, the `2N^(2)` gives the maximum number of electron possible in a given orbit or energy level. Thus, first orbit or K shell will have 2 electrons.Second orbit or L - shell will have 8 electrons. Third orbit or M Shell will have 18 electrons. If it is the outermost orbit then it should have not more than 8 electrons.There should be step - wise filling of electrons in DIFFERENT orbits i.e., electrons are not accompanied in a given orbit if the EARLIER orbits or shells are incompletely filled. | |
| 992. |
Summarise the rules for writing of distribution of electrons in various shells for the first eighteen elements. |
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Answer» Solution :The rules for writing the distribution of electrons in VARIOUS shells are as follows (1) The maximum number of electrons present in a shell is given by the FORMULA `2n^(2)` where N is the ORBIT number or energy level index, 1,2,3,.... The maximum number of electrons in different shells are first orbit or K shell will be `2 xx 1^(2)` = 2 . Second orbit or L shell will be 2` xx 2^(2) = 8` . Third orbit or M shell will be 2 `xx 3^(2) = 18`. Fourth orbit or N shell will be 2 ` xx 4^(2)` = 32 (2) The maximum number of electrons that can be accommodated in the outermost orbit is 8. (3) Electrons are not accommodated in a given shell, unless the inner shells are filled. i.e., shells are filled in a stepwise manner. Thus, eighteen electrons are accommodated as KLM 288 |
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| 993. |
Summarise the rules for writing of distribution of electrons in various shells for the first eighteen elements |
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Answer» Solution :The rules for WRITING of the distribution of etectrons in various shells for the first EIGHTEEN elements are given below. `to`Ifn gives the number of orbit or energy level, then `2N^(2)` gives the maximum number of electrons possible in a given orbit or energy level. THUS,First orbit or K-shell will have 2 electrons, Second orbit or L-shell will have 8 electrons, Third orbit or M-shell will have 18 electrons. `to`If it is the outermost orbit, then it should have not more than 8 electrons. `to ` There should be step-wise filling of electrons in different orbits, ie. electrons are not accompanied in a given orbit if the earlier orbits or shells are incompletely filled |
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| 994. |
Sulphuric acid is called King of Chemicals. Why is it called so? |
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Answer» Solution :Sulphuric acid is called King of Chemicals because it is USED in the preparation of many other compounds. It is used in car batteries ALSO Acids react with metallic OXIDES to give salt and water. `CaO+H_(2)SO_(4) to CaSO_(4)+H_(2)O` |
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| 995. |
Sulphur compounds in crude oil can be removed by using |
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Answer» COPPER oxide |
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| 996. |
(a) In which category of mixtures will alloys is classified and why ? (b) Solution is always a solid or liquid or gas.comment. (c) A solution is homogeneous or heterogeneous? |
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| 997. |
Suggest separation technique(s) one would need to employ to separate the following mixtures. (a) Mercury and water (b) Potassium chloride and ammonium chloride (c) Common salt, water and sand (d) Kerosene oil, water and salt |
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Answer» Solution :(a) Separation can be done with a separating funnel. Mercury being heavy forms lower layer. (b) Sublimation can be used. Ammonium chloride sublimes. (c ) Filtration followed by crystallisation TECHNIQUES can be used here. SAND can be removed as an insoluble residue upon filtration. Upon evaporating the filtrate in a china dish to about one third followed by slow colling crystals of common salt (NaCl) are formed. (d) KEROSENE OIL can be separated with a separating funnel. What and salt can be separated either by distillation (water distils) or by evaporation (water evaporates). Salt is left BEHIND as residue. |
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| 998. |
Suggest a method of separation for a mixture of sodium chloride and ammonium chloride. Explain the process. |
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Answer» Solution :Mixture of NACL and `NH_(4)Cl` can be separated by sublimation. Process Ammonium chloride and sodium chloride mixture is TAKEN ina porcelain dish. It is covered by an inverted funnel. The opening of the stem of the funnel is closed by means of a cotton plug. The outside of the funnel is kept cool by wrapping with wet blotting paper. On heating the porcelain dish, ammonium chloride changes into vapour state, which on coming in contact with the inner wall of the cooled funnel CONDENSES into the original solid and GETS collected there. |
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| 999. |
Sugar is dissolved in a cup of water at 30^(@)C. If it is heated, then _______ . |
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Answer» crystals are formed |
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| 1000. |
Sudha met with a fire accident. What kind of drug(s), she must take? |
| Answer» SOLUTION :ANALGESICS are to be ADMINISTERED to reduce the pain FOLLOWED by ANTIBIOTICS to prevent infection by microbes. | |