Chapter – 2
Chapter Solutions Assertion Reason Questions
In the following questions, a statement of assertion followed by a statement of reason is given. Choose
the correct answer out of the following choice.
(a) Assertion and reason both are correct statements but the reason is the correct explanation for assertion.
(b) Assertion and reason both are correct statements but the reason is not a correct explanation for assertion.
(c) Assertion is a correct statement but the reason is a wrong statement.
(d) Assertion is a wrong statement but the reason is correct
Assertion Reason Questions
Que 1. Assertion: Ice melts faster at high altitudes.
Reason: At high altitudes atmospheric pressure is high.
Ans 1. (d)
Explanation: Ice melts slowly at high altitude because melting is favoured at high pressure at high altitude the atmospheric pressure is low and so the ice melts slowly.
Que 2. Assertion: The addition of ethylene glycol (non–volatile) to water lowers the freezing point of water hence used as antifreeze
Reason: Heat must be removed from the water to make it freeze.
Ans 2. (c)
Explanation: Ethylene glycol is used as antifreeze, and it is a non-volatile substance that cannot evaporate into gas under certain conditions. If a substance is non-volatile then it has a high boiling point and low vapour pressure. Ethylene glycol is miscible in water in all proportions.
Que 3. Assertion: In an ideal solution, ∆mixH is zero.
Reason: In an ideal solution, A – B interactions are lower than A-A and B-B interactions.
Ans 3. (c)
Explanation: In an ideal solution, A−B…A−B interactions are the same as A−A…A−A and B−B..B−B interaction
Que 4. Assertion: Molarity of a solution in liquid state changes with temperature.
Reason: The volume of a solution changes with change in temperature
Ans 4. (a)
Explanation: Molarity (M) represents the number of moles of the solute dissolved per litre of solution.
Since the volume of a liquid varies with changes in temperature, the volume of the solution would also change while the number of moles of solute present in it will remain the same (or unchanged). This, therefore, would affect the molarity of the solution.
Que 5. Assertion: Molecular mass of benzoic acid when determined by colligative properties is found high.
Reason: Dimerization of benzoic acid.
Ans 5. (a)
Explanation: Colligative properties are the properties of solutions containing non-volatile solute. It is correct that the molecular mass of benzoic acid when determined by colligative properties is found abnormally high. This is because dimerisation of benzoic takes place in solution resulting in high molecular mass. Therefore, assertion and reason are true and the reason is the correct explanation.
Chapter Solutions Assertion Reason Questions
Que 6. Assertion: The freezing of water is an endothermic process.
Reason: Heat must be removed from the water to make it freeze.
Ans 6. (d)
Explanation: When water is cooled, it freezes. Thus to freeze water, heat must be removed from it. Hence the freezing of water is an exothermic process.
Que 7. Assertion: Osmosis does not take place in two isotonic solutions separated by a semi-permeable membrane.
Reason: Isotonic solutions have the same osmotic pressure.
Ans 7. (a)
Explanation: It could be the movement of water (osmosis), or other (diffusion). If a cell is placed in an isotonic solution, that means the amount of stuff inside the cell and outside the cell is equal. There will be some movement of water and salt across the cell membrane, but there will be no net concentration change.
Que 8. Assertion: If a liquid solute more volatile than the solvent is added to the solvent, the vapour pressure of the solution may increase i.e., ps > po.
Reason: In the presence of a more volatile liquid solute, only the solute will form the vapours and solvent will not.
Ans 8. (c)
Explanation: Both the solute and solvent will form the vapours but the vapour phase will become richer in the more volatile component.
Que 9. Assertion: If one component of a solution obeys Raoult’s law over a certain range of composition, the other component will not obey Henry’s law in that range.
Reason: Raoult’s law is a special case of Henry’s law
Ans 9. (b)
Que 10. Assertion: Use of pressure cooker reduces cooking time.
Reason: At higher pressure cooking occurs faster. [AIIMS 2000]
Ans 10. (a)
Explanation: It is fact that the use of a pressure cooker reduces cooking time because, at higher pressure over the liquid due to the cooker lid, the liquid boils at a higher temperature and cooking occurs faster.
Chapter Solutions Assertion Reason Questions
Que 11. Assertion: Lowering of vapour pressure is not dependent on the number of species present in the solution.
Reason: Lowering of vapour pressure and relative lowering of vapour pressure are colligative properties.
Ans 11. (d)
Explanation: Lowering of vapour pressure is directly proportional to the number of species present in the solution. Only relative lowering of vapour pressure is a colligative property
Que 12. Assertion: Azeotropic mixtures are formed only by non-ideal solutions and they may have boiling points either greater than both the components or less than both components.
Reason: The composition of the vapour phase is the same as that of the liquid phase of an azeotropic mixture.
Ans 12. (b)
Explanation: Non-ideal solutions with positive deviation i.e., having more vapour pressure than expected, boil at a lower temperature while those with negative deviation boil at a higher temperature than those of the components.
Que 13. Assertion: The molecular weight of acetic acid determined by the depression in the freezing point method in benzene and water was found to be different.
Reason: Water is polar and benzene is non-polar
Ans 13. (a)
Explanation: Depression in freezing point is a colligative property that depends upon the number of particles. The number of particles is different in the case of benzene and water that is why the molecular weight of acetic acid determined by the depression in the freezing point method is also different.
Que 14. Assertion: On adding NaCl to water its vapour pressure increases.
Reason: The addition of non-volatile solute increases the vapour pressure.
Ans 14. (d)
Explanation: If a non-volatile solute is added to water its vapour pressure always decreases. Therefore, both assertion and reason are false
Que 15. Assertion: CCl4 and H2O are immiscible.
Reason: CCl4 is a polar solvent. [AIIMS 2002]
Ans 15. (c)
Explanation: The assertion that CCl4 & H2O are immiscible is true because CCl4 is a non-polar liquid while water is polar hence assertion is true and the reason is false.
Chapter Solutions Assertion Reason Questions
Que 16. Assertion: 1 M solution of KCl has greater osmotic pressure than 1 M solution of glucose at the same temperature.
Reason: In solution, KCl dissociates to produce more number of particles.
Ans 16. (a)
Explanation: For NaCl, i =2, while for glucose, i = 1. Hence, the osmotic pressure of NaCl is higher than that of glucose solution.
Que 17. Assertion: When methyl alcohol is added to water, the boiling point of water increases.
Reason: When a volatile solute is added to a volatile solvent elevation in boiling point is observed.
Ans 17. (d)
Explanation: When methyl alcohol is added to water, the boiling point of water decreases because when a volatile solute is added to a volatile solvent elevation in boiling point is observed.
Que 18. Assertion: Azeotrope mixtures are formed by only non-ideal solution.
Reason: Azeotrope mixture can’t be separated by fractional distillation.
Ans 18. (b)
Explanation: Non-ideal solutions with positive deviation i.e., having more vapour pressure than expected, boil at a lower temperature while those with negative deviation boil at a higher temperature than those of the components.
Que 19. Assertion: Two liquids nitric acid and water form a maximum boiling azeotrope when mixed in the ratio of 68% and 32% respectively.
Reason: Interaction between nitric acid and water are stronger than nitric acid – nitric acid interactions and water-water interactions.
Ans 19. (a)
Que 20. Assertion: Isotonic solutions do not show the phenomenon of osmosis.
Reason: Isotonic solutions have equal osmotic pressure.
Ans 20. (b)
Explanation: It is true that the isotonic solution doesn’t show the phenomenon of osmosis. Isotonic solution is that solution that has the same osmotic pressure. Here both assertion and reason are true but the reason is not the correct explanation.
Chapter Solutions Assertion Reason Questions
