Element having highest $I.P.$ value is

The image of the point $(1, 2, -1)$ on the plane containing the line $\frac{x+1}{-3}=\frac{y-3}{2}=\frac{z+2}{1}$ and the point $(0, 7, -7)$ is:

If $u=\sin ^{-1}\left(\frac{x^2+y^2}{x+y}\right)$ then $x \frac{\partial u}{\partial x}+y \frac{\partial u}{\partial y}$ is equal to:

If in a regular polygon,the number of diagonals is $54$,then the number of sides of the polygon is:

Two wires of the same material and length but diameters in the ratio $1:2$ are stretched by the same force. The elastic potential energy per unit volume for the wires,when stretched by the same force,will be in the ratio: (in $:1$)

$2\,g$ of steam condenses when passed through $40\,g$ of water initially at $25\,^{\circ}C$. The condensation of steam raises the temperature of water to $54.3\,^{\circ}C$. What is the latent heat of steam in $cal/g$?