The difference in the lengths of a mean solar day and a sidereal day is about........$min$.

Match List-$I$ with List-$II$.

List-$I$	List-$II$
$(a)$ ${R}_{H}$ (Rydberg constant)	$(i)$ ${kg} {m}^{-1} {s}^{-1}$
$(b)$ $h$ (Planck's constant)	$(ii)$ ${kg} {m}^{2} {s}^{-1}$
$(c)$ $u_{B}$ (Magnetic field energy density)	$(iii)$ ${m}^{-1}$
$(d)$ $\eta$ (Coefficient of viscosity)	$(iv)$ ${kg} {m}^{-1} {s}^{-2}$

Choose the most appropriate answer from the options given below:

Find the rate of change of the volume of a sphere with respect to its surface area when the radius is $2 \ cm$.

Match List-$I$ with List-$II$:

List-$I$	List-$II$
$(A)$ Young's Modulus	$(I)$ $[ML^{-1}T^{-1}]$
$(B)$ Torque	$(II)$ $[ML^{-1}T^{-2}]$
$(C)$ Coefficient of Viscosity	$(III)$ $[M^{-1}L^3T^{-2}]$
$(D)$ Gravitational Constant	$(IV)$ $[ML^2T^{-2}]$

Choose the correct answer from the options given below:

Which of the following represents the fundamental forces of nature?

The density of water is $1000 \; kg \; m^{-3}$. The density of water vapour at $100^{\circ} C$ and $1 \; atm$ pressure is $0.6 \; kg \; m^{-3}$. The volume of a molecule multiplied by the total number gives what is called molecular volume. Estimate the volume of a water molecule.