1 mole = 24dm^3, which is 24,000cm^3
The problem states 50 cm^3, so we need to use the 24,000 cm^3 number.
Volume of gas at room temperature = number of moles x 24,000 cm^3
50 cm^3 = number of moles x 24,000 cm^3
Number of moles = 50 cm^3 / 24,000 cm^3
Number of moles = 0.00208333 (round answer as needed)