$A$ wheel completes $2000$ revolutions to cover a distance of $9.5\, km$. The diameter of the wheel is:

Estimate the average mass density of a sodium atom assuming its size to be about $2.5 \; \mathring{A}$. (Use the known values of Avogadro's number and the atomic mass of sodium). Compare it with the mass density of sodium in its crystalline phase: $970 \; kg \; m^{-3}$. Are the two densities of the same order of magnitude? If so,why?

$0.1 \, Pa = \dots \, Nm^{-2} = \dots \, \text{dyne} \, cm^{-2}$.

The density of a substance is $4 \, g/cc$ in a system in which the unit of length is $5 \, cm$ and the unit of mass is $20 \, g$. The density of the substance in the $CGS$ system is: (in $units$)

Which of the following pairs does not have similar dimensions?

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