Answer in one sentence

1. What is the common name of Na₂CO₃?

Ans. The common name of Na₂CO₃ is soda ash.

2. Name a sodium compound used for softening hard water.

Ans. Sodium carbonate (Na₂CO₃) is used for softening hard water.

3. What is efflorescence?

Ans. The phenomenon of spontaneous giving up of water of crystallization from a salt when it is exposed to air or warmed is called efflorescence.

4. Name two compounds which show efflorescence.

Ans. Na₂CO₃.10H₂O (washing soda) and FeSO₄.7H₂O (green vitriol)

5. Which compound is used as an antacid in medicine?

Ans. Sodium hydrogen carbonate (NaHCO₃) is used as an antacid in medicine.

6. Name the compound of calcium used for disinfecting drinking water.

Ans. Chloride of lime (CaOCl₂) is used for disinfecting drinking water

7. Name the real bleaching agent present in bleaching powder.

Ans. Chlorine (Cl₂) is a real bleaching agent present in bleaching powder.

8. What is Mohr’s salt?

9. How is Mohr’s salt prepared?

Ans. When ferrous Sulphate is reacted with ammonium Sulphate, Mohr’s salt is formed.

FeSO₄ + (NH₄)₂ SO₄ + 6H₂O → FeSO4 (NH₄)₂SO₄.6H₂O

Ans. Mohr’s Salt: FeSO₄ (NH₄)₂SO₄.6H₂O

10. Name the compound of calcium used for white wash for walls.

Ans. Calcium carbonate (chalk) CaCO₃ is used for white wash for walls.

11. Name the compound of copper used in preparing Bordeaux mixture.

Ans. The compound used in preparing Bordeaux mixture is copper Sulphate. 

12. Name the constituents of Bordeaux mixture.

Ans. The constituents of Bordeaux mixture are copper sulphate and lime (CaO).

13. Name the solution used to determine sugar in the urine.

Ans. Benedict’s solution is used to determine sugar in the urine.

14. Name the raw material used in the preparation of Plaster of Paris. Write its chemical formula.

Ans. Raw material : Gypsum

Chemical formula: CaSO₄. 2H₂O

15. Name a calcium compound, which hardens on setting with water.

Ans. Plaster of Paris hardens on setting with water.

16. Write the equation to show the reaction between Plaster of Paris and water.

Ans. (CaSO₄)₂ H₂O + 3H₂O → 2(CaSO₄.2H₂O)

17. Name the compound of calcium used in making toys and statues.

Ans. Plaster of Paris is used in making toys and statues.

18. Name the compound used in the purification of drinking water by decantation of suspended particles.

Ans. Potash alum [K₂SO₄, Al₂(SO₄)24 H₂O] is used in the purification of drinking water by decantation of suspended particles.

19. Name a calcium compound used for making wall surfaces smooth before painting them.

Ans. Plaster of Paris is used for making wall surfaces smooth before painting them.