Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :
- Both Statement I and Statement II are correct
- Statement I is correct but Statement II is incorrect
- Both Statement I and Statement II are incorrect
- Statement I is incorrect but Statement II is correct
Answer
(1) Both Statement I and Statement II are correct
Solution
Salt of weak acid + weak base: pH = 7 + 12(pKa - pKb)
∵ pH depends only on Ka (acid) and Kb (base) ⇒ Statement II is correct.
(NH4)2CO3: Kb(NH3) = 1.8 10-5
Ka(H2CO3) = 4.3 10-7
∵ Kb > Ka ⇒ CO32- hydrolyses more than NH4+ ⇒ solution is basic ⇒ Statement I is correct.
Answer: (1)