0.22g of a colourless oxide of nitrogen occupies 112 ml at STP. The compound is:?

Molar mass of gas at STP = 22400 ml/mol
Number of moles of the compound = (112 ml) / (22400 ml/mol) = 0.005 mol

Molar mass of the compound = (0.22 g) / (0.005 mol) = 44 g/mol

Molar mass some common oxides of nitrogen :
Molar mass of NO = (14 + 16) g/mol = 30 g/mol
Molar mass of NO₂ = (14 + 16×2) g/mol = 46 g/mol
Molar mass of N₂O = (14×2 + 16) g/mol = 44 g/mol

Hence, the compound is : N₂O

Gas laws.....

PV = nRT ............ ideal gas equation
PV = mRT / M...... n=m/M ..... m=mass, M=molar mass
M = mRT / (PV) ... solve for molar mass
M = 0.22g x 0.08206 Latm/molK x 273K / 1.00 atm / 0.112L
M = 44.0 g/mol

Oxides of nitrogen.... and their molar masses in g/mol
N2O, NO, NO2 .... 44.0, 30.0, 46.0

The gas can't be NO2 which is brick red. N2O is a colorless gas. Therefore, based on the match for color and molar mass, the gas is nitrous oxide, N2O.

try using a website called Mathway that may help with the math side of things.

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