Which unit is used for measuring atomic mass?

64.2 L

Explanation:

In order to be able to calculate the volume of oxygen gas produced by this reaction, you need to know the conditions for pressure and temperature.

Since no mention of those conditions was made, I'll assume that the reaction takes place at STP, Standard Temperature and Pressure.

STP conditions are defined as a pressure of

100 kPa

and a temperature of

0

∘

C

. Under these conditions for pressure and temperature, one mole of any ideal gas occupies

22.7 L

- this is known as the molar volume of a gas at STP.

So, in order to find the volume of oxygen gas at STP, you need to know how many moles of oxygen are produced by this reaction.