Class 10 Chemistry Chapter 2 - Acids and Bases Most Important Questions

 Class 10 - Acids and Bases 

Most Important Questions:- 

Q1. What will be the action of the following substances on litmus paper?

a) Dry HCI gas

b) Moistened NH3 gas

c) Lemon juice

d) Carbonated soft drinks

e) Curd

f ) Soap solution

Answer:

a) Dry HCI gas: Dry HCl gas would not affect the litmus paper.

b) Moistened NH3 gas: Moistened NH3 gas is alkaline in nature. Thus it will turn red litmus blue.

c) Lemon juice: Lemon juice is acidic in nature. Thus it will turn blue litmus red.

d) Carbonated soft drinks: Carbonated soft drinks contains carbonic acid. Thus it will turn blue litmus red.

e ) Curd: Curd contains lactic acid. Thus it will turn blue litmus red.

f)Soap solution: Soap is a salt of a strong base. Thus it will turn red litmus blue.

Q2. What are acids and Bases ? Explain with example .

Answer :- 

Acids :- Acids are those which produce H+ 

Ions in aqueous sulutions and are sour in taste .

E.g - HCL , HNO3 , HCO3 etc.

Base :- Base are those which produce OH- ions in aqueous solutions and are bitter in taste .

E.g - NaOH , Ca(OH)2 , Mg(OH)2 etc.

Q3. Arrange them according to increasing pH number . 

 NaOH , CH3COOH , HCl , Mg(OH)2 , Water 

Answer :- 

HCl < CH3COOH < Water < Mg(OH)2 < NaOH 

Q4. What happens when nitric acid is added to the eggshells?

Answer:

Eggshells contain calcium carbonate. Calcium carbonate reacts with nitric acid to form calcium nitrate and carbon dioxide gas.

CaCO3 (s) + HNO3 (aq) → CaNO3 (aq) + CO2 (g) + H2O (l)

Q 5. A Substance 'X ' When reacts with water produce two gases Hydrogen and 'Y' at cathode and anode . When 'Y ' react with 

Slaked lime produce another substance 'Z' .

Identify X , Y , Z and Write Chemical Equation.

Answer :- 

X - NaCl ( Sodium Chloride)

Y - Cl (Chlorine)

Z - CaOCl2 ( Bleaching Powder ) 

2NaCl + 2H20 → 2NaOH + H2 + Cl2 

Ca(OH)2 + Cl2 → CaOCl2 + H20

Q6. Salt A is commonly used in bakery products on heating gets converted into another salt B, which is used to remove the hardness of water, and a gas C is evolved. The gas C, when passed through lime water, turns it milky. Identify A, B and C.

Answer:

Baking powder is the salt used in bakery products that give sodium carbonate, and carbon dioxide gas on heating.

2 NaHCO3 → Na2CO3 + H2O + CO2

Sodium carbonate is used to remove the hardness of the water.

Carbon dioxide turns lime water milky due to the formation of insoluble calcium carbonate.

CO2 + Ca(OH)2 → CaCO3 + H2O.

Thus, A is sodium bicarbonate (Baking powder), B is sodium carbonate, and C is carbon dioxide gas.

Q7. For making cake, baking powder is taken. If your mother uses baking soda instead of baking powder in cake at home,

(a ) How will it affect the taste of the cake and why?

(b ) How can baking soda be converted into baking powder?

(c ) What is the role of tartaric acid added to baking soda?

Answer:

(a ) If we use baking soda instead of baking powder, the taste of the cake will be bitter. On heating baking soda, sodium carbonate will be formed, which will make the cake taste bitter.

2 NaHCO3 + Heat → Na2CO3 + CO2 + H2O

(b ) Baking soda can be converted to baking powder by adding an edible weak acid like tartaric acid in the baking soda.

(c ) When tartaric acid is dissolved in water, it liberates hydrogen ions. Hydrogen ions react with sodium carbonate to release carbon dioxide gas, which will make the cake fluffy.

Q8. What is Neutralization reaction ?

Answer :- 

When Acids and Bases reacts with each other to produce salt and Water . It is called neutralization reaction .