Question

How many times a $0.1$ $M$ strong monobasic acid solution should be diluted so that $pH$ of the resulting solution is tripled?

• A. $50$
• B. $10$
• C. $25$
• D. $100$
• E. $1000$

Answer 1

The correct option is D $100$

Given that

Monobasic acid $=0.1M$

Let consider the acid is $HCl$

then,

$H^{+}=0.1$

$pH=-\log \left(0.1\right)=1$

According to question the resulting $pH$ after dilution should be tripled.

means $pH=3$

$\left[H^{+}\right]={10}^{-3}$

Assume if $Vml$ of $0.1M$ solution were taken initially then, volume required to get $0.001M$ concentration

$M_1{V}_1=M_2{V}_2$

$0.1V=0.001V_2$

$V_2=100V$

100 times dilution is required.
Option D is correct.