Ageochemist 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