Step`1
The gas is assumed to be ideal.
--------------------
Step 2
Standard temperature and pressure => STP
STP is known to be:
Temperature = 0 °C = 273 K
Pressure = 1 atm (but today it is used 1 bar)
--------------------
Step 3
It is known that at SPT conditions:
1 mole of any gas = 22.4 L
Procedure:
1 mole of gas (STP) -------- 22.4 L of gas
3.2 moles of gas (STP) -------- X
X = 3.2 moles of gas (STP) x 22.4 L of gas/1 mole of gas (STP) = 71.7 L
Answer: Volume = 71.7 L