Round the number $234555359$ to $3$ significant figures.

Observe the following:
$I) 0.0063$
$II) 132.00$
$III) 1004$
The number of significant figures in $I, II$ and $III$ is respectively:

The density of mercury is $13.6 \, g/cm^3$. Find the mass of $1 \, L$ of mercury. (in $, g$)

The sum of three values $12.0$, $19.034$ and $2.0143$ is equal to $X$. The number of significant figures in $X$ is

The diameter of a zinc atom is $2.6 \, \mathring{A}$. Calculate $(a)$ the radius of the zinc atom in $pm$ and $(b)$ the number of atoms present in a length of $1.6 \, cm$ if the zinc atoms are arranged side by side lengthwise.

Fill in the blanks given below:
$(i)$ At ........ ${\,^\circ }{\text{C}}$,the values of temperature in both ${\,^\circ }{\text{C}}$ and ${\,^\circ }{\text{F}}$ are equal.
$(ii)$ The number of significant figures in $0.03$ is .....
$(iii)$ The closeness of various measurements for the same quantity is called .........
$(iv)$ The agreement of a particular value to the true value of the result is called ....