$1 \, fm = ...... \, m$.

What is a physical quantity? Write its types.

Which of the following is not a unit of time?

Explain this statement clearly: "To call a dimensional quantity 'large' or 'small' is meaningless without specifying a standard for comparison". In view of this,reframe the following statements wherever necessary:
$(a)$ atoms are very small objects
$(b)$ a jet plane moves with great speed
$(c)$ the mass of Jupiter is very large
$(d)$ the air inside this room contains a large number of molecules
$(e)$ a proton is much more massive than an electron
$(f)$ the speed of sound is much smaller than the speed of light.

$A$ new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes $8 \; min$ and $20 \; s$ to cover this distance?

Density of wood is $0.5 \; g/cm^3$ in the $CGS$ system of units. The corresponding value in $MKS$ units is?