An unknown diatomic gas has a density of 1.250 g/L at STP. What is the identity of the gas? (Enter the formula of the gas. Omit states-of-matter from your answer.)

Answer 1

one mole of gas occupies 22.4 L at STP

the molar mass of the gas is ... 1.250 g/L * 22.4 L = ?

solve for the molar mass of the gas
... then find the atomic molar mass for the "di"atomic gas
... look up the gas in the periodic table

enter the diatomic formula