When the time period of a sound wave is 0.08s, then what is its frequency?

The relationship between time period and frequency is given as:

Frequency $\left(f\right)=1 / T$(time period).
According to the question given,
Time period $\left(T\right)=0.08 \mathrm{s}$
Frequency $\left(f\right)=1 / T$
$f=1 / 0.08=100 / 8$

$f=12.5 \mathrm{Hz}$