Given, $v=320 \mathrm{m} {\mathrm{s}}^{-1}, l=1 \mathrm{m}$

For an organ pipe whose one end is closed, only odd harmonics containing odd multiples of fundamental frequency are present.

Resonate frequency of the first mode, $n_1=\frac{v}{4l^{\prime }}$

Second mode, $n_2=3n_1,$

Third mode, $n_3=5n_1,$

Fourth mode, $n_4=7n_1,$

Fifth mode, $n_5=9n_1$

So, $n_1=\frac{320}{4}=80 \mathrm{Hz}$

$n_2=3\times 80=240 \mathrm{Hz}$

$n_3=5\times 80=400 \mathrm{Hz}$

$n_4=7\times 80=560 \mathrm{Hz}$

$n_5=9\times 80=720\mathrm{ }\mathrm{Hz}$

So $\mathrm{160 }\mathrm{Hz}$  is not possible