The number of significant figures in $6.0023$ are

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 ........

In the final answer of the expression $\frac{(29.2 - 20.2)(1.79 \times 10^5)}{1.37}$,the number of significant figures is

$3.00 \ kg$ is equal to how many yards? Given: $1 \ kg = 1000 \ m$,$1 \ m = 1.094 \ yards$.

According to the significant figure convention, the result obtained by adding $12.11$, $18.0$, and $1.012$ is:

Find the number of electrons that generate $1$ coulomb charge?