$A$ student is to answer $10$ out of $13$ questions in an examination such that he must choose at least $4$ from the first $5$ questions. The number of choices available to him is

The thermally most stable compound is:

The equation $16 x^2+y^2+8 x y-74 x-78 y+212=0$ represents:

The length of the tangent drawn to the circle $x^2+y^2-2x+4y-11=0$ from the point $(1,3)$ is:

The pressure of an ideal gas varies with volume as $P = \alpha V$,where $\alpha$ is a constant. One mole of the gas is allowed to undergo expansion such that its volume becomes $m$ times its initial volume. The work done by the gas in the process is

In an $AC$ circuit,the current is given by $i = 5 \sin(100t - \frac{\pi}{2}) \text{ A}$ and the $AC$ potential is $V = 200 \sin(100t) \text{ V}$. Then the power consumption is $....$ watt.