Of the following quantities,which one has dimensions different from the remaining three?

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?

Mention the $MKS$ and $CGS$ units of work,define them,and write the dimensional formula of work.

The mechanical equivalent of heat $J$ is

The speed of light in vacuum is taken as unity. If light takes $6 \text{ min } 40 \text{ s}$ to reach the Earth from the Sun, the distance between the Sun and the Earth in new units is:

$A$ new unit $(\alpha)$ of length is chosen such that it is equal to the speed of light in vacuum. What is the distance between Venus and Earth in terms of $\alpha$ units if light takes $6 \text{ min } 40 \text{ s}$ to cover this distance (in $\text{ } \alpha$)?