Which of the following reagents reacts with benzaldehyde to produce $1$-phenylethanol?

$A$ bar magnet of length $3 \, cm$ has points $A$ and $B$ along its axis at distances of $24 \, cm$ and $48 \, cm$ from the center on opposite sides. The ratio of the magnetic fields at these points is:

Which one of the following statements is correct with respect to basic character?

$A$ ray of light is incident on an equilateral glass prism placed on a horizontal table. For minimum deviation,which of the following is true?

Name the gas that can readily decolourise acidified $KMnO_4$ solution.

The $P-V$ diagram of a diatomic gas is a straight line passing through the origin. The molar heat capacity of the gas in this process will be: