If the speed of light is $3.0 \times 10^8 \ ms^{-1}$,calculate the distance covered by light in $2.00 \ ns$. (in $m$)

$1 \, \mu g = ........ \, mg$

The incorrect rule regarding the determination of significant figures is

Perform the following calculations for the given exponential numbers:
$(i)$ $(6.7 \times 10^4) \times (8.4 \times 10^7)$
$(ii)$ $\frac{(3.4 \times 10^{-3})}{(6.5 \times 10^{-7})}$

From the following masses,the one which is expressed nearest to the milligram is (in $g$)

One fermi is $....$ (in $cm$).