a 16 gram sample of oxygen has a volume of 11.2L at standard pressure . what is the temp of the oxygen ?

Answer 1

Use PV = nRT
n = grams/molar mass O2
Solve for T (in kelvin)

Answer 2

so when i get my answer
i add 273 to it?

Answer 3

Maybe yes, maybe no, but definitely you don't add 273.
If you want T in kelvin that is your answer. If you want it in degrees C, you subtract 273 from the calculation.
K = 273 + C