Page No 18:
Question 1:
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
Page No 22:
Question 1:
Why should curd and sour substances not be kept in brass and copper vessels?
Page No 22:
Question 2:
Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
Page No 25:
Question 1:
Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?
Page No 25:
Question 4:
While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
Page No 25:
Question 5:
How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?
Page No 25:
Question 6:
How is the concentration of hydroxide ions (OH−) affected when excess base is dissolved in a solution of sodium hydroxide?
Page No 28:
Question 1:
You have two solutions, A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic?
Page No 28:
Question 2:
What effect does the concentration of 
ions have on the nature of the solution?
Page No 28:
Question 4:
Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?
Page No 33:
Question 2:
Name the substance which on treatment with chlorine yields bleaching powder?
Page No 33:
Question 4:
What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.
Page No 34:
Question 1:
A solution turns red litmus blue, its pH is likely to be
(a) 1 (b) 4 (c) 5 (d) 10
Page No 34:
Question 7:
Why does distilled water not conduct electricity, whereas rain water does?
Page No 35:
Question 9:
Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is
(a) neutral?
(b) strongly alkaline?
(c) strongly acidic?
(d) weakly acidic?
(e) weakly alkaline?
Arrange the pH in increasing order of hydrogen-ion concentration.
Page No 35:
Question 10:
Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH3COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why?
Page No 35:
Question 11:
Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.
Page No 35:
Question 12:
A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
Page No 35:
Question 13:
Plaster of Paris should be stored in a moisture-proof container. Explain why?
ions? If yes, then why are these basic?
