10th class Chemistry, Chapter 20: Water MCQs

1. The pH of distilled water is:

1. (A) 6.5
2. (B) 8.5
3. (C) 7 ✓
4. (D) 7.5

2. The unpleasant odours in water can be removed by:

1. (A) adding chlorine
2. (B) treating it with activated charcoal ✓
3. (C) sedimentation
4. (D) filtration

3. The source of harmful microbes in natural water:

1. (A) human and animal wastes ✓
2. (B) fertilizers used for crops
3. (C) industrial waste-water
4. (D) microbes in rocks

4. Which gases are dissolved in natural water from the atmosphere through diffusion?

1. (A) O₂ and CO₂
2. (B) N₂ and CO₂
3. (C) O₂ and N₂
4. (D) O₂, N₂ and CO₂ ✓

5. The fertilizer harmful to paddy rice is:

1. (A) Super phosphate
2. (B) Ammonium nitrate ✓
3. (C) Urea
4. (D) Potassium sulphate

6. Fertilizers which increase the resistance of plants towards diseases and make plants strong by healthy root development are:

1. (A) Nitrogenous fertilizers
2. (B) Phosphate fertilizers
3. (C) Potassium fertilizers ✓
4. (D) Magnesium fertilizers

7. Hydrated copper (II) sulphate (CuSO₄·5H₂O) is ____ in colour.

1. (A) blue ✓
2. (B) white
3. (C) black
4. (D) green

8. Anhydrous copper (II) sulphate is:

1. (A) yellow
2. (B) white ✓
3. (C) blue
4. (D) red

9. A drop of water on anhydrous CuSO₄ changes its colour from:

1. (A) blue to green
2. (B) blue to white
3. (C) white to black
4. (D) white to blue ✓

10. Heating hydrated copper sulphate makes it lose:

1. (A) water molecules ✓
2. (B) oxygen
3. (C) copper
4. (D) sulphur

11. Pure water boils at ____ under standard conditions.

1. (A) 90 °C
2. (B) 100 °C ✓
3. (C) 110 °C
4. (D) 0 °C

12. The presence of impurities in water ____ its boiling point.

1. (A) reduces to 0
2. (B) decreases
3. (C) slightly increases ✓
4. (D) does not change

13. Impurities in water ____ its melting point.

1. (A) double
2. (B) raise
3. (C) lower ✓
4. (D) do not change

14. Tap water has a pH range of:

1. (A) 1 to 3
2. (B) 6.5 to 8.5 ✓
3. (C) 9 to 12
4. (D) 3 to 5

15. Tap water contains minerals like salts of:

1. (A) lead only
2. (B) iron only
3. (C) calcium and magnesium ✓
4. (D) sodium only

16. Distilled water is a ____ conductor of electricity.

1. (A) metallic
2. (B) excellent
3. (C) good
4. (D) bad ✓

17. Distilled water is ideal for use in:

1. (A) drinking only
2. (B) gardens only
3. (C) fire fighting
4. (D) laboratories, medical procedures and the pharmaceutical industry ✓

18. Oxygen enters natural water from the atmosphere through:

1. (A) filtration
2. (B) diffusion ✓
3. (C) distillation
4. (D) evaporation

19. Aquatic plants and algae produce oxygen by:

1. (A) respiration
2. (B) photosynthesis ✓
3. (C) digestion
4. (D) fermentation

20. Which of the following is a heavy metal?

1. (A) Potassium
2. (B) Sodium
3. (C) Calcium
4. (D) Lead ✓