Why does methyl orange show different colours in acidic and basic media?

Correct answer: Because it is an indicator and changes colour with the medium

Methyl orange is an acid-base indicator. Its molecular structure changes as the hydrogen-ion concentration of the medium changes, producing different colours: it is generally red in an acidic solution and yellow in a basic or sufficiently neutral solution, with an orange transition range. Therefore its colour provides evidence about the nature of the medium; it is not a gas-forming or metal-producing substance.