Class 10 Science Acid Bases and salts

Class 10 Science Acid Bases and salts

 

Class 10 Science Acid Bases and salts Fill in the blanks , Multiple Choice Question [mcq] and True false .

 

Fill in the Blanks

 

1. __________ is a natural indicator that turns red in acidic solutions and blue in basic solutions. Answer: Litmus

2. Acids produce __________ ions in water, which are responsible for their acidic properties. Answer: hydrogen/H+

3. The reaction between an acid and a base to give a salt and water is known as a __________ reaction. Answer: neutralization

4. On the pH scale, a neutral solution has a pH value of __________. Answer: 7

5. When acids react with metals, __________ gas is evolved. Answer: hydrogen

6. All metal carbonates react with acids to give a corresponding salt, carbon dioxide and __________. Answer: water

7. The process of dissolving an acid or base in water to decrease the concentration of ions is called __________. Answer: dilution

8. The chemical formula of baking soda is __________. Answer: NaHCO₃

9. __________ is used for making toys, materials for decoration and for making surfaces smooth. Answer: Plaster of Paris

10. The pH of acid rain is less than __________. Answer: 5.6

11. The chlor-alkali process produces sodium hydroxide, hydrogen, and __________ gas. Answer: chlorine

12. The chemical name of bleaching powder is __________. Answer: calcium oxychloride/Ca(ClO)₂

13. Salts of a strong acid and a weak base are __________ in nature with pH value less than 7. Answer: acidic

14. The chemical name of washing soda is __________. Answer: sodium carbonate/Na₂CO₃.10H₂O

15. Tooth decay starts when the pH of the mouth is lower than __________. Answer: 5.5

 

Multiple Choice Questions

 

1. Which of the following is not an olfactory indicator?
a) Vanilla
b) Onion
c) Phenolphthalein
d) Clove
Answer: c) Phenolphthalein

 

2. When electricity is passed through an aqueous solution of sodium chloride, which of the following forms at the anode?
a) Hydrogen
b) Chlorine
c) Sodium hydroxide
d) Oxygen
Answer: b) Chlorine

 

3. What is the common name of calcium sulphate hemihydrate?
a) Gypsum
b) Plaster of Paris
c) Bleaching powder
d) Baking soda
Answer: b) Plaster of Paris

 

4. The pH of human blood is normally around:
a) 5.5
b) 7.0
c) 7.4
d) 8.5
Answer: c) 7.4

 

5. Which of the following is not a product of the chlor-alkali process?
a) Sodium hydroxide
b) Chlorine
c) Hydrogen
d) Sodium carbonate
Answer: d) Sodium carbonate

 

6. The formula of water of crystallization in washing soda is:
a) Na₂CO₃.5H₂O
b) Na₂CO₃.10H₂O
c) Na₂CO₃.2H₂O
d) Na₂CO₃.H₂O
Answer: b) Na₂CO₃.10H₂O

 

7. Which substance is added to make baking powder?
a) Tartaric acid
b) Citric acid
c) Sulphuric acid
d) Hydrochloric acid
Answer: a) Tartaric acid

 

8. Which gas is produced when an acid reacts with a metal carbonate?
a) Oxygen
b) Hydrogen
c) Carbon dioxide
d) Nitrogen
Answer: c) Carbon dioxide

 

9. Bee sting contains:
a) Methanoic acid
b) Acetic acid
c) Tartaric acid
d) Citric acid
Answer: a) Methanoic acid

 

10. An aqueous solution of which of these will not conduct electricity?
a) Hydrochloric acid
b) Glucose
c) Sodium hydroxide
d) Sulphuric acid
Answer: b) Glucose

 

11. Which of the following is used for removing permanent hardness of water?
a) Sodium chloride
b) Sodium carbonate
c) Sodium hydrogencarbonate
d) Calcium carbonate
Answer: b) Sodium carbonate

 

12. Which of the following will produce a gas that turns lime water milky?
a) HCl + NaOH
b) HCl + Na₂CO₃
c) H₂SO₄ + NaCl
d) HNO₃ + KOH
Answer: b) HCl + Na₂CO₃

 

13. Which solution has the highest concentration of hydrogen ions?
a) pH = 3
b) pH = 5
c) pH = 7
d) pH = 10
Answer: a) pH = 3

 

14. Neutralization is a reaction between:
a) Acid and acid
b) Base and base
c) Acid and base
d) Salt and water
Answer: c) Acid and base

 

15. What happens when Plaster of Paris is mixed with water?
a) It forms gypsum
b) It releases carbon dioxide
c) It becomes acidic
d) It forms calcium carbonate
Answer: a) It forms gypsum

 

True or False

 

1. Acids taste bitter while bases taste sour.
False – Acids taste sour while bases taste bitter

2. When hydrochloric acid reacts with sodium hydroxide, the products are sodium chloride and water.
True

3. An aqueous solution with a pH of 3 is more acidic than a solution with a pH of 5.
True

4. The universal indicator shows different colors at different concentrations of hydroxide ions in a solution.
True

5. Metal oxides are acidic in nature.
False – Metal oxides are basic in nature

6. Adding water to concentrated acid is considered a safe laboratory practice.
False – Acid should always be added to water, not the other way around

7. Both acids and bases can conduct electricity in their aqueous solutions.
True

8. The nettle sting contains acetic acid which causes pain and irritation.
False – Nettle sting contains methanoic acid

9. Plaster of Paris is chemically calcium sulphate hemihydrate.
True

10. Mixing an acid or base with water results in an increase in the concentration of ions per unit volume.
False – It results in a decrease in the concentration of ions (dilution)

11. Hydrogen ions can exist alone in an aqueous solution.
False – Hydrogen ions exist as hydronium ions (H₃O⁺) in aqueous solutions

12. Baking soda is a strong base.
False – Baking soda is a mild base

13. Salts of a strong acid and a strong base are neutral with a pH value of 7.
True

14. Carbon dioxide gas turns lime water milky due to the formation of calcium carbonate.
True

15. All bases dissolve in water to form alkalis.
False – Only bases that are soluble in water are called alkalis