moles of CO gas : 1.545
Standard conditions for temperature and pressure are used as a reference in certain calculations or conditions
There are 2 conditions that are usually used as a reference : STP and RTP
Assuming the STP state :
Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters / mol.
Then for 34.6 L of CO gas :
[tex]\tt moles=\dfrac{34.6}{22.4}=1.545[/tex]