MCQ
The $pH$ of a solution is $5.0$. To this solution sufficient acid is added to decrease the $pH$ to $2.0$. The increase in hydrogen ion concentration is.....$times$
  • A
    $100$
  • B
    $10$
  • $1000$
  • D
    $2.5$

Answer

Correct option: C.
$1000$
c
Formula for $pH$ is $pH =-\log \left[ H ^{+}\right]$

When $pH =5$,

$\left[ H ^{+}\right]=10^{- pH }=10^{-5}\, M$

The $pH$ of solution is decreased to $2 .$

When $pH =2$,

$\left[ H ^{+}\right]=10^{- pH }=10^{-2} \,M$

The change in concentration of $\left[ H ^{+}\right]$is $10^{-2} / 10^{-5}=10^3=1000.$

It is increased by $1000$ times.

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