A gas has a volume of 3.75 liters at 35 degrees C and 0.850 atm. What
volume would it have, in liters, at 20 degrees C and 910 torr?
a. 1.34
b. 6.29
c. 2.53
d. 5.69

Hello!!

We can use the Combined Gas Law:
The combined gas law deals with gas systems where the quantity of the
gas is kept constant. It permits the treatment of changes of state
where five of the six possible variables are given.
The math expression for the Combined Gas Law is as follows: 
P1.V1 / T1 = P2.V2 / T2  

Solving for V2 we have:
V2 = (P1.V1.T2)/(T1.P2) 

P1 = 0.85 atm
V1 = 3.75 L
T1 = (273+35)K = 308K
P2 = 910 torr = 1.1973683 atm =    (1 atm = 760 torr)
V2 = ?
T2 = (273+20)K = 293K

V2 = (0.85 atm x 3.75 L x 293K)/(308K x 1.1973683 atm) = 
   = (933.9375/368.90294364) L = 2.53 L

The correct answer is c.

I hope this helps you.

Regards.
livioflores-ga