In $20\,\, ml \,\,0.4 \,M-HA$ solution, $80\,\, ml$ water is added. Assuming volume to be additive, the $pH$ of final solution is

$(K_a \,\,of\,\, HA = 4 \times 10^{-7} ,\, log\,2 = 0.3)$

  • A

    $4.30$

  • B

    $3.75$

  • C

    $3.40$

  • D

    $3.70$

Similar Questions

The $pH$ of $0.1$ $M$ solution of cyanic acid $(HCNO)$ is $2.34$. Calculate the ionization constant of the acid and its degree of ionization in the solution.

What is the $pH$ of $0.001 \,M$ aniline solution? The ionization constant of aniline can be taken from Table . Calculate the degree of ionization of aniline in the solution. Also calculate the ionization constant of the conjugate acid of aniline.

Base $K _{ b }$
Dimethylamine, $\left( CH _{3}\right)_{2} NH$ $5.4 \times 10^{-4}$
Triethylamine, $\left( C _{2} H _{5}\right)_{3} N$ $6.45 \times 10^{-5}$
Ammonia, $NH _{3}$ or $NH _{4} OH$ $1.77 \times 10^{-5}$
Quinine, ( $A$ plant product) $1.10 \times 10^{-6}$
Pyridine, $C _{5} H _{5} N$ $1.77 \times 10^{-9}$
Aniline, $C _{6} H _{5} NH _{2}$ $4.27 \times 10^{-10}$
Urea, $CO \left( NH _{2}\right)_{2}$ $1.3 \times 10^{-14}$

The ${K_b}$ of ammonia is $1.8 \times {10^{ - 5}}$ at $298$ $K$ temperature. Calculate the $pH$ of $0.1$ $M$ solution. 

The ionization constant of $HF$, $HCOOH$ and $HCN$ at $298\, K$ are $6.8 \times 10^{-4}, 1.8 \times 10^{-4}$ and  $4.8 \times 10^{-9}$ respectively. Calculate the ionization constants of the corresponding conjugate base.

Values of dissociation constant, $K_a$ are given as follows

      Acid       $K_a$
      $HCN$       $6.2\times 10^{-10}$
      $HF$       $7.2\times 10^{-4}$
      $HNO_2$       $4.0\times 10^{-4}$

Correct order of increasing base strength of the base $CN^-,F^-$ and $NO_2^-$ will be

  • [JEE MAIN 2013]