question_answer

Ionisation constant of \[C{{H}_{3}}COOH\] is \[1.7\times {{10}^{-5}}\] and concentration of \[{{H}^{+}}\] ions is \[3.4\times {{10}^{-4}}\]. Then find out initial concentration of \[C{{H}_{3}}COOH\] molecules:     [AIPMT 2001]

A)  \[3.4\times {{10}^{-4}}\]

B)                   \[3.4\times {{10}^{3}}\]

C)  \[6.8\times {{10}^{-4}}\]

D)                   \[6.8\times {{10}^{-3}}\]        

Correct Answer: D

Solution :

Given that

for

is weak acid, so in it  is equal to initial concentration. Hence,