$A, B$ and $C$ are three points in a uniform electric field as shown in the figure. The electric potential is

If $\hat{i}+2 \hat{j}+3 \hat{k}$ and $3 \hat{i}+2 \hat{j}+\hat{k}$ are sides of a parallelogram, then a unit vector parallel to one of the diagonals of the parallelogram is

The amount of work done in blowing a soap bubble such that its diameter increases from $d$ to $D$ is ($T$ = surface tension of solution).

The coefficient of $x^{10}$ in the expansion of $(2+3x)e^{-x}$ is

$A$ block of $200 \ g$ mass moves with a uniform speed in a horizontal circular groove,with vertical side walls of radius $20 \ cm$. If the block takes $40 \ s$ to complete one round,the normal force by the side walls of the groove is:

$\int \frac{dx}{1-\cos x-\sin x}$ is equal to