JEE Main Solved Paper 2017 Question 5
Question: $ p{K_a} $ of a weak acid (HA) and $ p{K_b} $ of a weak base (BOH) are 3.2 and 3.4, respectively. The pH of their salt (AB) solution is [JEE Main Solved Paper-2017]
Options:
A) 7.2
B) 6.9
C) 7.0
D) 1.0
Show Answer
Answer:
Correct Answer: B
Solution:
- Given $ pK _{a}(HA)=3.2 $ $ pK _{b}(BOH)=3.4 $ As given salt is of weak acid and weak bas
$ \therefore $ $ pH=7+\frac{1}{2}pK _{a}-\frac{1}{2}pK _{b} $ $ =7+\frac{1}{2}(3.2)-\frac{1}{2}(3.4) $ $ =6.9 $
