Question

One mole of an ideal monoatomic gas is mixed with $1$ mole of an ideal diatomic gas. The molar specific heat of the mixture is:

• A. $9cal$
• B. $8cal$
• C. $3cal$
• D. $4cal$

Answer 1

The correct option is D $4cal$

$C_v=\frac{3}{2}R$ ( for monoatomic)

$C_v=\frac{5}{2}R$ ( for diatomic)

Thus for mixture:

$C_v=\frac{[\frac{3}{2}R+\frac{5}{2}R]}{2}$

$=2R=2\times 2cal$

$=4cal$

Hence, the correct answer is option D.