What is the simplest formula for a compound containing 0.50 mol na, 0.50 mol s, and 0.75 mol o?

We need to get the mole ratio between the elements. To do this, we will divide by the the smallest number of moles given as follows:

0.5 mole of Na / 0.5 = 1

0.5 mole of S / 0.5 = 1

0.75 mole of O / 0.5 = 3/2

Now, we need to get rid of the fractions. To do this, we will multiply all the ratios by 2:

Na = 1 x 2 = 2

S = 1 x 2 = 2

O = 3/2 x 2 = 3

So, in the simplest formula, the ratio Na:S:O is 2:2:3

This can be written as: Na2S2O3 which is known as sodium thiosulphate.