A tuning fork is used to produce resonance in glass tube. The length of the air column in this tube can be adjusted by a variable piston. At room temperature of ${27}^{\mathrm{ o}}\mathrm{C}$ two successive resonances are produced at $20 \mathrm{cm}$ and $73 \mathrm{cm}$ of column length. If the frequency of the tuning fork is $320 \mathrm{Hz}$, the velocity of sound in air at ${27}^{\mathrm{ o}}\mathrm{C}$ is

• A

  $350 \mathrm{m} {\mathrm{s}}^{-1}$
• Correct answer
  B

  $339 \mathrm{m} {\mathrm{s}}^{-1}$
• C

  $330 \mathrm{m} {\mathrm{s}}^{-1}$
• D

  $300 \mathrm{m} {\mathrm{s}}^{-1}$

Hence, the correct answer is option: 'B'.