Answer:
2.1 atm
Step-by-step explanation:
We are given the following variables to work with:
Initial pressure (P1): 2.5 atm
Initial temperature (T1): 320 K
Final temperature (T2): 273 K
Constant volume: 7.0 L
We are asked to find the final pressure (P2). Since volume is constant, we want to choose a gas law equation that relates initial pressure and temperature to final pressure and temperature. Gay-Lussac's law does this:

We can rearrange the law algebraically to solve for
.

Substitute your known variables and solve:
