In CBSE Class 10 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.
Here, we have provided case based/passage based questions for Class 10 Science Chapter 2 Acids, Bases and Salts.
Case Study/Passage Based Questions
pH is quite useful to us in a number of ways in daily life. Some of its applications are:
Control of pH of the soil : Plants need a specific pH range for proper growth. The soil may be acidic, basic or neutral depending upon the relative concentration of H* and OH-. The pH of any soil can be determined by using pH paper. If the soil is too acidic, it can be corrected by adding lime to it. If the soil is too basic, it can be corrected by adding organic manure which contains acidic materials.
Regaining shine of a tarnished copper vessel by use of acids : A copper vessel gets tarnished due to formation of an oxide layer on its surface. On rubbing lenion on the vessel, the surface is cleaned and the vessel begins to shine again. This is due to the fact that copper oxide is basic in nature, which reacts with the acid (citric acid) present in lemon to form a salt (copper citrate) which is washed away with water. As a result, the layer of copper oxide is removed from the surface of the vessel and the shining surface is exposed.
Self-defence by animals through chemical warfare : Stings of bees and ants contain methanoic acid. When stung, it causes lot of pain and irritation. This can be cured by rubbing the affected area with mild base like baking soda.
(i) When black copper oxide placed in a beaker is treated with dilute HCl, its colour changes to
(b) dark red
(c) bluish green
(d) no change.
AnswerAnswer: (c) bluish green
(ii) P is an aqueous solution of acid and Q is an aqueous solution of base. When these two are diluted separately, then
(a) pH of P increases while that of Q decreases till neutralisation.
(b) pH of P decreases while that of Q increases till neutralisation.
(C) pH of both P and Q decrease.
(d) pH of both P and Q increase.
AnswerAnswer: (a) pH of P increases while that of Q decreases till neutralisation.
(iii) Which of the following acids is present in bee sting?
(a) Formic acid
(b) Acetic acid
(c) Citric acid
(d) Hydrochloric acid
AnswerAnswer: (c) Citric acid
(iv) Sting of ant can be cured by rubbing the affected area with soap because
(a) it contains oxalic acid which neutralises the effect of formic acid
(b) it contains aluminium hydroxide which neutralises the effect of formic acid
(c) it contains sodium hydroxide which neutralises the effect of formic acid
(d) none of these
AnswerAnswer: (c) it contains sodium hydroxide which neutralises the effect of formic acid
(v) The pH of soil X is 7.5 while that of soil Y is 4.5. Which of the two soils, should be treated with powdered chalk to adjust its pH?
(a) X only
(b) Y only
(c) Both X and Y
(d) none of these