A 400-L Container Is Divided into Two Equal Parts by a a Rubber

Multiple Choice

A 40.0-L container is divided into two equal parts by a rubber membrane. One half of the container has $1.50$ moles of an ideal monatomic gas at $250 \mathrm {~K}$ , and the other half is a vacuum. The container is well insulated, so there is no exchange of heat with the surroundings. The membrane breaks, and eventually the gas reaches a new equilibrium condition occupying the entire volume. What is the final temperature of the gas?

A) $125 \mathrm {~K}$
B) $100 \mathrm {~K}$
C) $157 \mathrm {~K}$
D) $180 \mathrm {~K}$
E) $250 \mathrm {~K}$