40 calories of heat is needed to raise the temperature of 1 mol of an ideal monoatomic gas from \[20{}^\circ C\] to \[30{}^\circ C\] at a constant pressure. The amount of heat required to raise its temperature over the same interval at a constant volume (R = 2 cal/mol/K) is

• A. 20 cal
• B. 40 cal
• C. 60 cal
• D. 80 cal