If $n(A) = 3$,$n(B) = 6$ and $A \subseteq B$,then the number of elements in $A \cup B$ is:

$A$ hollow pipe of length $0.8 \ m$ is closed at one end. At its open end,a $0.5 \ m$ long uniform string is vibrating in its second harmonic and it resonates with the fundamental frequency of the pipe. If the tension in the wire is $50 \ N$ and the speed of sound is $320 \ ms^{-1}$,the mass of the string is: (in $g$)

The $INCORRECT$ statement about the dissolution of an alkali metal in liquid ammonia is

The volume of one mole of the gas is changed from $V$ to $2 V$ at constant pressure $p$. If $\gamma$ is the ratio of specific heats of the gas, what is the change in internal energy of the gas?

$A$ ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and each one is equal to $3/4$th the angle of the prism. The angle of deviation is (in $^{\circ}$)

In the Liebermann's nitroso reaction,the sequential changes in the colour of phenol occur as: