To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 3.4-L bulb, then filled it with the gas at 1.40atm and 25.0 ∘C and weighed it again. The difference in mass was 5.5g . Identify the gas.

Answer 1

Use PV = nRT. You know T, R, V and P. Solve for n = number of mols, then n = grams/molar mass. Plug in g and solve for molar mass. Divide that by 2 (because it's X2) and identify from the periodic table.

Answer 2

N2