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

Define density and provide its $SI$ unit.

$4 \ L \ atm$ is equal to (in $cal$)

How many significant figures should be present in the answer of the following calculations?
$(i)$ $\frac{0.02856 \times 298.15 \times 0.112}{0.5785}$
$(ii)$ $5 \times 5.364$
$(iii)$ $0.0125 + 0.7864 + 0.0215$

If the density of a solution is $3.12 \ g/mL$,the mass of $1.5 \ mL$ solution in significant figures is ............ $g$

$68 \, ^\circ F = ........ \, K.$