Page 31 - Chemistry - XI

Q10. In an accident in a school lab, a large sample of aqueous NaOH was spilt. Which of the following
is not suitable for neutralising the alkali spill as it leaves corrosive liquid?
(a) Na CO (b) Oxalic acid (c) conc. H SO (d) NaHSO
2 3 2 4 4
Q11. Freshly distilled water has a pH = 7. After it was left standing for a short time, the pH was
observed to have dropped to below 7.0. Which of the following explains it?

(a) HCl → H + Cl (b) H O H + OH –
–
+
+

2
(c) CO + H O 2− + 2H + (d) NH (g) + H O NH + OH –
+
CO

2 2 3 3 2 4
Q12. When 2.0 M of an acid X and 2.0 M solution of an alkali are mixed together, which of the
following is an indication that they have reacted?
(a) A gas is evolved. (b) A white ppt is formed.
(c) The reaction mixture becomes hot. (d) The solution changes colour.
Q13. Which of the following deductions can be made about acids X and Y?
X Y
Conductivity 400 ms 7.0 ms

Temperature change when excess of acid 6.9°C 6.7°C
reacts with 100 mL of 1 M NaOH

Reaction with Mg H gas produced rapidly H gas produced slowly
2 2

(a) X is weak acid, Y is strong acid. (b) X is strong acid, Y is weak acid.
(c) Both X and Y are strong acids. (d) Both X and Y are weak acids.

Q14. Which of the following is not true for all alkalis?
(a) They are electrolytes.
(b) They turn universal indicator purple.
(c) They precipitate bases from many salt solutions.

(d) They react with ammonium salts to give NH gas.
3
Q15. In group 2, how does pH vary by adding HCl before passing H S gas?
2
(a) Decreases (b) Increases (c) Remains the same (d) Can’t be predicted
Q16. Suggest suitable replacement for NH Cl in NH OH + NH Cl
4 4 4
(a) (NH ) CO (b) NH NO (c) HCl (d) NH
4 2 3 4 3 3
Q17. Which of the following when added decreases pH of NH OH?
4
(a) NaOH (b) KOH (c) NH Cl (d) NaCl
4
Answer key

1. (a), 2. (a), 3. (a), 4. (b), 5. (a), 6. (a), 7. (d), 8. (a), 9. b), 10. (c), 11. (c), 12. (c), 13. (b), 14. (b),
15. (a), 16. (b), 17. (c)

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