Given $P = 0.0030 \ m$,$Q = 2.40 \ m$,$R = 3000 \ m$. The significant figures in $P, Q$,and $R$ are respectively:

Convert the following into basic $SI$ units:
$(i)$ $28.7 \, pm$
$(ii)$ $15.15 \, pm$
$(iii)$ $25365 \, mg$

Fill in the blanks given below:
$(i)$ The symbol for the quantity of luminous intensity is .......... and the name of its $SI$ unit is ......... .
$(ii)$ The prefixes used for $10^{-18}$ and $10^{18}$ are ............ and ........... respectively.
$(iii)$ The $SI$ unit of density is ......... .
$(iv)$ In the ........ unit of temperature,its negative value is not possible.

Which of the following relations for expressing the volume of a sample is not correct?

What is the range of magnitude in chemistry measurements?

$2 \times 10^{8}$ atoms of carbon are arranged side by side. Calculate the radius of a carbon atom if the length of this arrangement is $2.4 \, cm$.