What is the colour of methyl orange in acidic solution and why is it useful?

Correct answer: Red because it helps identify acid

The governing concept is the colour change of an acid–base indicator. Methyl orange is red in an acidic solution and changes through an orange transition range toward yellow in an alkaline solution. Because the colour depends on the solution’s pH, it helps distinguish acidic and alkaline conditions during testing or titration. Option B describes its alkaline colour incompletely, while C and D give incorrect colours and interpretations. Therefore A is correct.