Question

If 0.765g of an unknown gas were collected at 741 torr and 95C in a 245 mL container, then what is the molecular weight of this unknown gas?

Answer 1

just use:
pV= nRT
from there calculate "n"
and then use:
n= m/M -> M=m/n

Answer 2

just be careful about units, temperature in K, pressure in Pa, volume in m3, R=8,314 JK-1mol-1