Answer: The number of moles of gas added to the container are 5.82
Step-by-step explanation:
Avogadro's law states that volume is directly proportional to number of moles at constant temperature and pressure.
The equation used to calculate number of moles is given by:

where,
and
are the initial volume and number of moles
and
are the final volume and number of moles
Putting values in above equation, we get:

number of moles of gas added to the container = (9.33-3.51) = 5.82
Thus the number of moles of gas added to the container are 5.82