\[ \text{Ph–CH(OH)–CHO} \xrightarrow[\text{H}_2\text{O}]{\text{HO}^-} Q \] P and Q are isomers. Identify Q.
A particle is moving in a straight line. The variation of position $ x $ as a function of time $ t $ is given as: $ x = t^3 - 6t^2 + 20t + 15 $. The velocity of the body when its acceleration becomes zero is: