Which of the following physical quantities can be used to express temperature?

How many astronomical units $(AU)$ make $1$ parsec?

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.

If ${u_1}$ and ${u_2}$ are the units selected in two systems of measurement and ${n_1}$ and ${n_2}$ are their respective numerical values,then:

Match List-$I$ with List-$II$ and select the correct answer by using the codes given below the lists.

List-$I$	List-$II$
$(A)$ Distance between earth and stars	$(1)$ Microns
$(B)$ Inter-atomic distance in a solid	$(2)$ $\mathring{A}$s
$(C)$ Size of the nucleus	$(3)$ Light years
$(D)$ Wavelength of infrared laser	$(4)$ Fermi

What is a unit? What are fundamental units and derived units?