Spraying of $D.D.T.$ on crops produces pollution of

The bonds present in ${N_2}{O_5}$ are ........

Which of the following is the strongest acid?

If $3 \sin x + 4 \cos x = 5$,then $6 \tan \frac{x}{2} - 9 \tan^2 \frac{x}{2}$ is equal to

$A$ uniform but time-varying magnetic field $B(t)$ exists in a circular region of radius $a$ and is directed into the plane of the paper,as shown. The magnitude of the induced electric field at point $P$ at a distance $r > a$ from the centre of the circular region is:

In the circuit shown in the adjoining figure,the reading of the ammeter is .............. $A$.