The units nanometer and picometer are related as,

Which of the following is correct?

How is $5000$ represented with $3$ significant figures?

Fill in the blanks given below:
$(i)$ The instrument used to measure the mass of a single atom is .......
$(ii)$ The sum of the mole fractions of all components in a solution is always .......
$(iii)$ The $SI$ unit of volume is ........

Convert the following pressure values into atmosphere $(atm)$:
$(a)$ $735 \ torr$
$(b)$ $985 \ mbar$
$(c)$ $1.42 \times 10^5 \ Nm^{-2}$

$5 \times 10^2 \, cm = .......... \, dm$