A geochemist has determined by measurements that there are 33.7 moles of tin in a sample of cassiterite. how many moles of oxygen are in the sample?

67.4 mol of O atoms

Explanation:

Cassitrerite is a Tin Mineral having a chemical formula SnO₂. As seen in chemical formula there are two moles of Oxygen atoms for each Tin atom. So we can conclude that,

For,

1 mole of Sn in SnO₂ there are = 2 moles of O atoms

So for,

33.7 moles of Sn there will be = X moles of O atoms

Solving for X,

X = (33.7 mol of Sn * 2 mol of O) : 1 mol of Sn

X = 67.4 mol of O atoms