WBBSE Class 9 Physical Science MCQ Questions Chapter 4.6 Water

Well structured WBBSE Class 9 Physical Science MCQ Questions Chapter 4.6 Water can serve as a valuable review tool before exams.

Water Class 9 WBBSE MCQ Questions

Multiple Choice Questions :

Question 1.
The salt which is the cause of hardness of water :
(i) NH₄ Cl
(ii) NaNO₃
(iii) MgSO₄
(iv) K₂ SO₄
Answer:
(iii) MgSO₄

Question 2.
Soap is a salt of :
(i) Acetic acid
(ii) Palmitic acid
(iii) Formic acid
(iv) Nitric acid.
Answer:
(ii) Palmitic acid

Question 3.
Which of the following metals does not react with cold and hot water :
(i) Fe
(ii) K
(iii) Ni
(iv) Ag
Answer:
(iv) Ag

Question 4.
Which of the following is soft water:
(i) rain water
(ii) river water
(iii) tube well water
(iv) sea water
Answer:
(i) rain water

Question 5.
The salt which is the cause of temporary hardness :
(i) NaHCO₃
(ii) NaCl
(iii) Ca(HCO₃)₂
(iv) MgSO₄
Answer:
(iii) Ca(HCO₃)₂

Question 6.
Which of the following metals reacts easily with water at ordinary temperature :
(i) Ca
(ii) Zn
(iii) Cu
(iv) Ag
Answer:
(i) Ca

Question 7.
Tube well water becomes brown due to :
(i) Ca(HCO₃)₂
(ii) Fe(HCO₃)₂
(iii) MgSO₄
(iv) MgCl₂
Answer:
(ii) Fe(HCO₃)₂

Question 8.
D₂ O reacts with CaC₂ to form :
(i) C₂ D₂
(ii) CaD₂
(iii) Ca₂ D₂ O
(iv) CD₂
Answer:
(i) C₂ D₂

Question 9.
Permutit is regenerated by passing :
(i) 10% NaOH solution
(ii) 10% NH₄ Cl solution
(iii) 10% NaCl solution
(iv) none of these
Answer:
(iii) 10% NaCl solution.

Question 10.
If 1 lit. water contains 0.001 mol MgSO₄. What will be the hardness of water?
(i) 100 ppm
(ii) 200 ppm
(iii) 500 ppm
(iv) 150 ppm
Answer:
500 ppm

Question 11.
Water has high boiling point because :
(i) specific heat of water is high
(ii) heat of dissociation is high
(iii) presence of hydrogen bonding
(iv) molecules weight is low
Answer:
Presence of hydrogen bonding.

Question 12.
Anion exchange resin is regenerated by passing :
(i) dilute NaCl solution
(ii) dilute H₂ SO₄ solution
(iii) dilute HNO₃ solution
(iv) dilute NaOH solution
Answer:
dilute NaOH solution

Question 13.
When hard water is passed through zeolite, the Na (present in zeolite) is exchanged by :
(i) OH^–
(ii) Ca²⁺
(iii) \(\mathrm{SO}_4^{2-}\)
(iv) H⁺
Answer:
Ca²⁺

Question 14.
Water is oxidised to oxygen by :
(i) ClO₂
(ii) KMnO₄
(iii) H₂ O₂
(iv) F₂
Answer:
F₂

Question 15.
Sodium promptly reacts with water at ordinary temperature to form sodium hydroxide and what ?
(i) oxygen
(ii) nitrogen
(iii) chlorine
(iv) hydrogen
Answer:
hydrogen

Question 16.
Which state of water provides medium of life ?
(i) Solid
(ii) liquid
(iii) vapour
(iv) gas
Answer:
liquid.

Question 17.
Which property of water controls environmental temperature ?
(i) specific heat capacity
(ii) Latent heat of vaporisation
(iii) density
(iv) surface tension
Answer:
Specific heat capacity

Question 18.
Air obtained from dissolved air in water contain oxygen and nitrogen respectively in what percentage?
(i) 21% O₂, 78% N₂
(ii) 17% O₂, 83% N₂
(iii) 33% O₂, 66% N₂
(iv) 66% O₂, 33% N₂
Answer:
33% O₂, 66% N₂

Question 19.
What is the prescribed limits of pH of potable water?
(i) 4.5
(ii) 6.5-8.5
(iii) 1.5-4.5
(iv) 8.5-9.5
Answer:
6.5-8.5

Question 20.
Which of the following ions responsible for hardness of water?
(i) Fe²⁺
(ii) Na⁺
(iii) Cr³⁺
(iv) Mn²⁺
Answer:
Fe²⁺

Fill in the blanks :

1. _______ reacts with water at ordinary temperature.
Answer:
Calcium

2. Soft water readily forms lather with _______.
Answer:
soap

3. Water of sea, river are examples of _______ water.
Answer:
hard

4. By using _______ water thermal plants can cut water requirements by about 98%.
Answer:
recycled

5. Depletion of oxygen dissolved in water due to enhanced growth of algae is called _______.
Answer:
eutrophication

6. Elements having greater tendency to gain electrons from their solution are called _______ elements.
Answer:
electronegative

7. Deionised water contains only H⁺ cation and _______ anion.
Answer:
OH^–

8. A more reactive metal displaces a _________ reactive metal from the latter’s solution.
Answer:
less

9. Cation-exchanger resins contain COOH, _______ radicals.
Answer:
SO₃ H

10. Temporary hardness of water is due to presence of soluble _______
Answer:
bicarbonates

11. Permanent hardness of water is due to presence of dissolved chloride and _______ salts of Ca and Mg.
Answer:
sulphate

12. The class of water that does not easily form _______ with soap is called hard water.
Answer:
lather

13. The class of water that easily form lather with soap is called ______ water.
Answer:
soft

14. Water is a _______ solvent.
Answer:
versatile

15. Removal of both temporary and permanent hardness is done by ______ process.
Answer:
ion exchange

16. Removal of temporary hardness of water is done by _______.
Answer:
boiling

17. De-ionised water is made by _______.
Answer:
de-ioniser

18. Among river water, rain water and tubewell water, _______ is soft water.
Answer:
rain water

19. Cu does not react with _______ at ordinary temperature.
Answer:
water

20. The 97 % water of the total amount of earth’s water is called _______ water.
Answer:
underground

21. _______ is the chemical name of zeolite.
Answer:
Sodium aluminosilicate (Na₂ O, Al₂ O₃, 3 SiO₂, 2 H₂ O)

22. The permissible limit of arsenic in drinking water is _______.
Answer:
0.05 mg / L

23. Amberlite IR-120 is a useful _______ exchanger.
Answer:
cation

24. RSO₃ H is a ______ exchanger resin.
Answer:
cation

25. If pressure on the surface of water is increased, its boiling point and freezing point ______.
Answer:
increases, decreases.

26. Temporary hard water contains ______ salt of calcium, magnesium and iron.
Answer:
hydrogen carbonate

27. RNH₃⁺ OH – is ______ exchanger resin.
Answer:
anion