The density of gas containing chlorine and oxygen has density of 2.875 g/l at 756.0 mm Hg and 11 degrees Celsius what is the most likely molecular formula of the gas?

Answer 1

I think the problem is shaky or you omitted a word or two; I will ASSUME this is A gas (and not a mixture of gases Cl2 and O2).

P*molar mass = density x R x T
Solve for molar mass.