Here you are looking on the Free Body diagram of a net force of 0N in both the x and y-directions. the only ones that has that condition met is A and C.
An oxygen gas is a diatomic molecule which means that each molecule is composed of 2 atoms. Its symbol is O2.
Each oxygen atom has a molar mass of 16 g/mol. The molar mass of oxygen gas is calculated below,
molar mass = 2 x (16 g/mol) = 32 g/mol
To determine the number of moles in 52.5 grams of oxygen, divide the given mass by the calculated molar mass.
n = 52.5 grams / (32 gram/ mol)
n = 1.64 moles
Thus, there are 1.64 moles of oxygen gas.
Its okay my friend. you dont need to over stress it.