Explanation

(b) From the formula for speed of sound in air
$\frac{v_{1}}{v_{2}} = \sqrt{\left( \frac{T_{1}}{T_{2}} \right)}$
Or
$\frac{2}{2v} = \sqrt{\left( \frac{273 + 27}{T_{2}} \right)}$
Or
$\frac{1}{2} = \sqrt{\left( \frac{300}{T_{2}} \right)}$
Squaring the Eq. (i), we get
$\frac{1}{4} = \frac{300}{T_{2}}$
Or $T_{2} = 300 \times 4 = 1200K$
Or =1200-273=927°C