1. Rain water contain:
(A) Salts
(B) Suspended impurities
(C) Gases
(D) Biological impurities
2. Underground water contains:
(A) Gases
(B) Salts
(C) Suspended impurities
(D) Biological impurities
3. Water which gives lather when treated with soap is known as:
(A) Soft water
(B) Hard water
(C) Mineral water
(D) De-mineral water
4. By boiling water ______ hardness of water can be removed:
(A) Permanent
(B) Temporary
(C) Both a and b
(D) None of these
5. In zeolite method calcium and magnesium ions of hard water are replaced by:
(A) Zinc
(B) Iron
(C) Chromium
(D) Sodium
6. Compound which causes temporary hardness of water is:
(A) Ca(HCO₃)₂
(B) CaCl₂
(C) CaSO₄
(D) CaCO₃
7. Compound that causes temporary hardness of water is:
(A) Mg(HCO₃)₂
(B) MgCl₂
(C) MgSO₄
(D) MgCO₃
8. Boiling can remove ______ hardness of water:
(A) Permanent
(B) None of these
(C) Both a and b
(D) Temporary
9. Percentage of NaCl in sea water is:
(A) 5%
(B) 3.5%
(C) 2.5%
(D) 4%
10. Which one of the following compound causes temporary hardness of water?
(A) NaCl
(B) MgCl₂
(C) Ca(HCO₃)₂
(D) CaCl₂