Force acting on a particle moving in a straight line varies with the velocity of the particle as $F = \frac{K}{v}$. Here $K$ is a constant. The work done by this force in time $t$ is

If the wavelength of an electromagnetic radiation is $2000 \ \mathring{A}$,what is its energy in ergs?

$A$ convex lens is made up of three different materials as shown in the figure. For a point object placed on its axis,the number of images formed are

Three immiscible liquids of densities $d_1 > d_2 > d_3$ and refractive indices $\mu_1 > \mu_2 > \mu_3$ are put in a beaker. The height of each liquid column is $h/3$. $A$ dot is made at the bottom of the beaker. For near normal vision,find the apparent depth of the dot.

Arrange the following compounds in the increasing order of their dipole moment:
$(I)$ Toluene
$(II)$ $m$-Dichlorobenzene
$(III)$ $o$-Dichlorobenzene
$(IV)$ $p$-Dichlorobenzene

The $pH$ of $0.05 \ M$ acetic acid is $(K_a = 2 \times 10^{-5})$