answer
To answer this question, we can use the ideal gas equation to determine the number of mols
PV = nRT
P – pressure
V- volume
N – mols
R – gas constant
T – temperature in Kelvin
We can rearrange the equation to make N subject of the formula like so ;
n = PV/RT
= 0.745 atm x 7.8L/ 8.314 x 295
= 0.00237 mols
= 2.37 mmols