For an ideal gas

Density ρ = p x M/ RT

F rom the given data,

5.46 = 2 x M/ 300 x R ………(1)

ALSO ρ_{STP} = 1 x M/ 273 x R ………..(2)

FROM (1) & (2) ,WE GET

ρ_{STP = }(1 x M/ 273 x R) x (300 x R/ 2 x M)

= 300** /** 273 X 2 = 3.00 g/dm^{3}

Hence, the density of the gas at STP will be 3 g dm^{–3}.