Calculate the relative molecular mass of a gas if a 500cm3 sample at 20¢ªC and 1 atomic mass of 0.66g

Answer 1

I don't understand the "1 atomic mass of 0.66 g."

Answer 2

1 atmosphere=101.325 kpa
Use this to work out the pascal value and then use the ideal gas equation to find out the moles.
Once you have done this use the n=m/M equation to find out what the relative molecular mass is :)