How much energy in $kWh$ is obtained by eating an ice cream labeled as $700 \ kcal$?

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?

Identify the pair which has different dimensions.

Choose the physical quantity pair with the same dimensions.

In an experiment of measuring the refractive index of a glass slab using a travelling microscope in a physics lab,a student measures the real thickness of the glass slab as $5.25\,mm$ and the apparent thickness of the glass slab as $5.00\,mm$. The travelling microscope has $20$ divisions in $1\,cm$ on the main scale,and $50$ divisions on the Vernier scale are equal to $49$ divisions on the main scale. The estimated uncertainty in the measurement of the refractive index of the slab is $\frac{x}{10} \times 10^{-3}$,where $x$ is $..............$

The mechanical equivalent of heat $J$ is