How many moles of oxygen (o2) are present in 33.6 l of the gas at 1 atm and 0°c?
a: 1.5
b: 2
c: 22.4
d: 32

The condition at 1 atm and 0°C is considered "Standard Temperature and Pressure" (a.k.a STP). At STP, all gases have an approximate volume of 22.4 L/ 1 mol.

33.6 L* (1 mol/ 22.4 L)= 1.5 mol.
(Note that the unit cancels out so you get the answer)

The correct answer is A. 1.5~

Exothermic,  physical change after it is already baked