$70$ calories of heat is required to raise the temperature of $2$ moles of an ideal diatomic gas at constant pressure from $30°\mathrm{C}$ to $35°\mathrm{C}.$ The amount of heat required (in calories) to raise the temperature of the same gas through the same range ( $30°\mathrm{C}$ to $35°\mathrm{C}$ ) at constant volume is

• A

  $30$
• Correct answer
  B

  $50$
• C

  $70$
• D

  $90$

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