Water MCQs
Question 1. The mass ratio of hydrogen and oxygen in water is
(1) 2:1
(2) 1:2
(3) 1:8
(4) 8:1
Answer: (3) 1:8
Question 2. Who first recognised that water is a compound of two elements (hydrogen and oxygen) in 1783?
(1) Lavoisier
(2) Cavendish
(3) J. Thomson
(4) Robert Boyle
Answer: (1) Lavoisier
Question 3. What is the fundamental property that makes water so important?
(1) Density
(2) Its crystal structure
(3) Its boiling point
(4) Hydrogen bonds
Answer: (1) Density
Question 4. In pressure cooker, water boils at T°C; T is
(1) 100°C os
(2) > 100°C
(3) < 100°C
(4) None of these
Answer: (2) > 100°C
Question 5. At 3.98°C (nearly 4°C), water has a special property. What is this?
(1) Density is minimum
(2) Volume is maximum
(3) Density is maximum
(4) None of these
Answer: (3) Density is maximum
Question 6. Water can act as
(1) An. acid only
(2) A base only
(3) Both as acid and a base
(4) Neither acid nor base
Answer: (3) Both as acid and a base
Question 7. ppm is a unit sometimes used to express concentration level of pollutants in water. This ppm is equivalent to
(1) g/l
(2) ml/l
(3) Kg/ml
(4) mg/\(\mathrm{dm}^3\)
Answer: (2) ml/l
Question 8. Hard water contains appreciable amount of concentration of which ions ?
(1) \(\mathrm{Cl}^{-}\) and \(\mathrm{NO}^{-}\)
(2) \(\mathrm{Na}^{+}\) and \(\mathrm{K}^{+}\)
(3)\(\mathrm{CO}^{-2}\) and \(\mathrm{Cl}^{-}\)
(4) \(\mathrm{Ca}^{+2}\) \(\mathrm{Fe}^{+2}\) and \(\mathrm{Mg}^{+2}\)
Answer: (4) \(\mathrm{Ca}^{+2}\) \(\mathrm{Fe}^{+2}\) and \(\mathrm{Mg}^{+2}\)
Question 9. Temporary hardness is due to the presence of which compound in water?
(1) NaCl
(2) \(\mathrm{CaSO}_4\)
(3) \(\mathrm{NaNO}_3\)
(4) \(\mathrm{Ca}\left(\mathrm{HCO}_3\right)_2\)
Answer: (4) \(\mathrm{Ca}\left(\mathrm{HCO}_3\right)_2\)
Question 10. Which state of water provides the medium of life?
(1) Solid
(2) Liquid
(3) Vapour
(4) Vapour at 100°C.
Answer: (2) Liquid
Question 11. Which property of water controls environmental temperature?
(1) Specific heat capcity
(2) Latenet heat of vaporisation
(3) Density
(4) Surface tension.
Answer: (1) Specific heat capcity
Question 12. Air obtained from dissolved air in water contains oxygen and nitrogen respectively in the percentage
(1) 21% \(\mathrm{O}_2\), 78% \(\mathrm{N}_2\)
(2) 17% \(\mathrm{O}_2\), 83% \(\mathrm{N}_2\)
(Cc) 33%\(\mathrm{O}_2\), 66% \(\mathrm{N}_2\)
(4) 66% \(\mathrm{O}_2\), 33% \(\mathrm{N}_2\)
Answer: (3) 33% \(\mathrm{O}_2\) 66% \(\mathrm{N}_2\)
Question 13. What are the prescribed limits of pH of potable water?
(1) 4.5.
(2) 6.5-4.5
(3) 1.5-4.5
(4) 8.5-9.5
Answer: (2) 6.5-4.5
Question 14. Which of the following ions is responsible for the hardness of water?
(1) \(\mathrm{Fe}^{+2}\)
(2) \(\mathrm{Na}^{+}\)
(3)\(\mathrm{HCO}_3^{-}\)
(4)\(\mathrm{SO}_4^{2-}\)
Answer: (1) \(\mathrm{Fe}^{+2}\)
Question 15. The salt which is the cause of the hardness of water is
(1) \(\mathrm{NH}_4 \mathrm{Cl}\)
(2) \(\mathrm{NaNO}_3\)
(3) \(\mathrm{MgSO}_4\)
(4) \(\mathrm{K}^{2}{SO}_4\)
Answer: (3) \(\mathrm{MgSO}_4\)
Question 16. Soap is a salt of
(1) Acetic acid
(2) Palmitic acid
(3) Formic acid
(4) Nitric acid
Answer: (2) Palmitic acid
Question 17. Which of the following metals does not react with cold and hot water?
(1) Fe
(2) K
(©) Ni
(4) Ag
Answer: (4) Ag
Question 18. Which of the following is soft water?
(1) Rainwater
(2) River water
(3) Tubewell
(4) Seawater
Answer: (1) Rainwater
Question 19. Which of the following metals reacts easily with water at ordinary temperature?
(1) Ca
(2) Zn
(3) Cu
(4) Ag
Answer: (1) Ca
Question 20. Tubewell water becomes brown due to
(1)\(\mathrm{Ca}\left(\mathrm{HCO}_3\right)_2\)
(2) \(\mathrm{Fe}\left(\mathrm{HCO}_3\right)_2\)
(3) \(\mathrm{MgSO}_4\)
(4) \(\mathrm{MgCl}_2\)
Answer: (2) \(\mathrm{Fe}\left(\mathrm{HCO}_3\right)_2\)
Question 21. D2O reacts with CaC2 to form
(1) \(C_2 D_2\)
(2)\({Ca} D_2\)
(3)\(\mathrm{Ca}_2 \mathrm{D}_2 \mathrm{O}\)
(4)\(\mathrm{CD}_2\)
Answer: (1) \(C_2 D_2\)
Question 22. Permutit is regenerated by passing
(1) 10% NaOH solution
(2) 10% \(\mathrm{NH}_4 \mathrm{Cl}\) solution
(3) 10% NaCl solution
(4) None of these
Answer: (3) 10% NaCl solution
Question 23. If 1 lit. water contains 0.001 mol \(\mathrm{MgSO}_4\)what will be the hardness of water ?
(1) 100 ppm
(2) 200 ppm
(3) 500 ppm
(4) 150 ppm
Answer: (3) 500 ppm
Question 24. Water has high boiling point because
(1) Specific heat of water is high
(2) Heat of dissociation is high
(3) Presence of hydrogen bonding
(4) Molecule weight is low
Answer: (3) Presence of hydrogen bonding
Question 25. Anion exhange resin is regenerated by passing
(1) Dilute NaCl solution
(2) Dilute H2SO4 solution
(3) Dilute HNO3 solution
(4) Dilute NaOH solution
Answer: (4) Dilute NaOH solution
Question 26. When hard water is passed through zeolite, the Na* (present in zeolite) is exchanged by
(1) \(\mathrm{OH}^{-}\)
(2) \(\mathrm{Ca}^{+2}\)
(3) \(\mathrm{SO}^{-2}\)
(4)\(\mathrm{H}^{+}\)
Answer: (2) \(\mathrm{Ca}^{+2}\)
Question 27. Water is oxidised to oxygen by
(1) \(\mathrm{ClO}_2\)
(2) \(\mathrm{KMnO}_4\)
(3) \(\mathrm{H}_2 {O}_2\)
(4) \(\mathrm{F}_2\)
Answer: (4) \(\mathrm{F}_2\)
Question 28. Sodium promptly reacts with water at ordinary temperature to form sodium hydroxide and what?
(1) Oxygen
(2) Nitrogen
(3) Chlorine
(4) Hydrogen
Answer: (4) Hydrogen 3
