find the molar mass of 7.5gm of a gas occupying 5.8 lt volume at s.t.p.

1 answer

L is liters (or litres), not lt.

1 mole of a gas occupies 22.4 L at STP. So how many moles do you have? That's 5.8 L x (1 mol/22.4 L) = approx 0.25 but you need a more accurate answer than that. Then
mols = grams/molar mass. You have mols and grams, solve for molar mass.