I think, by convention, most would consider the solvent as the major component and the others as solutes. Actually, however, it dosesn't matter.

Question

I just read that when one liquid is dissolved in another, the minor component is usually considered the solute and the major component is the solvent. Now if you mix 3 liquid solvents(acetone, water and alcohol, would the solvents be all 3 or the ones with the most amount? eg. 50mL of acetone vs. 10mL of alcohol and 5mL of water?

I still need help whether the majority solvent is based on the one that has the most mL in the mixture.

what gas is formed when hydrochloric acid and mossy zinc are combined

You may use volume to determine the major component OR you may look up the densities and consider mass of each. It depends somewhat upon what you want to do with it. If this sounds confusing, I would go with volume.

hydrogen gas