The velocity of sound increases by 75 % when it enters a liquid from air the percentage increase in its wavelength is

$\begin{array}{l}{\mathrm{v}}_1=\mathrm{v}\\ {\mathrm{v}}_2=\mathrm{v}+\frac{75}{100}\mathrm{v}=1.75\mathrm{v}\\ \frac{{\mathrm{v}}_1}{{\mathrm{v}}_2}=\frac{{\mathrm{\lambda }}_1}{{\mathrm{\lambda }}_2}\\ \frac{{\mathrm{v}}_1}{1.75\mathrm{v}}=\frac{{\mathrm{\lambda }}_1}{{\mathrm{\lambda }}_2}\\ {\mathrm{\lambda }}_2=1.75{\mathrm{\lambda }}_1\end{array}$
Increase in wave length  $={\mathrm{\lambda }}_2-{\mathrm{\lambda }}_1$
$\begin{array}{l}=1.75{\mathrm{\lambda }}_1-{\mathrm{\lambda }}_1\\ =0.75{\mathrm{\lambda }}_1\end{array}$
Percentage increase in wave length  $=\frac{0.75 {\mathrm{\lambda }}_1}{{\mathrm{\lambda }}_1}\times 100$
= 75 %