Question

WILL MARK YOU BRAINLIEST AND GIVE YOU 15 POINTS!!

Answer 1

The answer to your question is a

Answer 2

1 mole of a gas at STP occupies volume = 22.4 L

And

1 mole of of an element has a mass = Gram molecular mass (if it is molecule and O2 at STP is a molecule O2) = 2 x (atomic mass) =2 x 16 = 32 g

Since 22.4 L at STP = 1 mole =32 g of O2.

Note:

Some gases are monoatomic (like He,Ar,Kr,Xe, etc) in these case 1 mole of gas ay STP will have mass equal to their gram atomic mass.