How does changing the ratio of nitrogen atoms and oxygen atoms change the compounds?

The elements in the compound are represented by their chemical symbols in a chemical formula and ratios of different elements are represented as subscripts on each chemical symbol.

The nitrogen and oxygen forms different compounds.

When the number of moles of both nitrogen and oxygen are present in same ratio i.e. 1:1:

When the number of moles of nitrogen is present in twice in numbers compared to the number of moles of oxygen, the ratio is 2:1:

When the number of moles of oxygen is present in twice in numbers compared to the number of moles of nitrogen, the ratio is 2:1:

When nitrogen is present in 2 moles and oxygen is present in 5 moles, the ratio is 2:5:

When nitrogen is present in 2 moles and oxygen is present in 4 moles, the ratio is 2:4:

Yes it would be a physical change.