During the titration of ammonium hydroxide (taken in a conical...

The titration is between ammonium hydroxide ($NH_4OH$), a weak base, and dilute hydrochloric acid ($HCl$), a strong acid.

The salt formed at the equivalence point is ammonium chloride ($NH_4Cl$), which undergoes cationic hydrolysis to give an acidic solution with a pH less than $7$.

For a strong acid-weak base titration, an indicator with a working pH range in the acidic region is required. Methyl orange, which has a pH range of $3.1$ to $4.4$, is the most suitable indicator.

Since the weak base ($NH_4OH$) is taken in the conical flask, the initial medium is basic. Methyl orange is yellow in a basic medium.

As the strong acid ($HCl$) is added from the burette, the pH decreases. At the end point, the solution becomes slightly acidic, and the colour of methyl orange changes to red.

Thus, the observed colour change at the end point is yellow to red.

Answer: Methyl orange, yellow to red