a
Given $\frac{v}{4 L}=412$
$\frac{\mathrm{v}}{\mathrm{L}}=1648$
When pipe is cut we will get one $COP$ and one $\mathrm{OOP}$
$\therefore $ Fundamental frequency of $COP$
$=\frac{\mathrm{v}}{4 \mathrm{L}}=\frac{\mathrm{v}}{4\left(\frac{\mathrm{L}}{2}\right)}=\frac{\mathrm{v}}{2 \mathrm{L}}=\frac{1648}{2}=824 \mathrm{\,Hz}$
And fundamental frequency of $OOP$
$=\frac{\mathrm{v}}{2 \mathrm{L}^{\prime}}=\frac{\mathrm{v}}{2\left(\frac{\mathrm{L}}{2}\right)}=\frac{\mathrm{v}}{\mathrm{L}}=1648 \mathrm{\,Hz}$