Available Answers

1. 1.

   Complete and balance the equations

   HARD & SOFT WATER a. Formation of temporary hard water	CaCO3 + H2O + CO2 → ___________ MgCO3 + H2O + CO2 → ___________
   b. Removal of temporary hardness in water - by boiling	Ca(HCO3)2 → ___________ ↓ + ___________ +___________ [g] Mg(HCO3)2 → ___________↓ + ___________ +___________ [g]
   c. Removal of temporary hardness in water - by addition of washing soda [Na2CO3]	Na2CO3 + Ca(HCO3)2 → ___________ ↓ + ___________
   d. Removal of permanent hardness in water - by addition of washing soda [Na2CO3]	Na2CO3 + CaSO4 → ___________ ↓ + ___________

    

2. 2.

   Name one substance which is 'deliquescent'.

3. 3.

   How does an increase in temperature affect:

   1. the solubility of NaCl,
   2. the solubility of CaSO₄ in water?
4. 4.

   Table salt becomes moist and sticky during the rainy season. Give reasons.

5. 5.

   A white powder forms on the surface of washing soda crystals which are left exposed to the air. Give reasons.

6. 6.

   Why is anhydrous CaCl₂ used in a desiccator. Name one substance which is 'efflorescent'.