State the $SI$ unit of thermodynamic temperature and provide an explanation for this unit.

If the value of Avogadro number is $6.023 \times 10^{23} \ mol^{-1}$ and the value of Boltzmann constant is $1.380 \times 10^{-23} \ J \ K^{-1}$,then the number of significant digits in the calculated value of the universal gas constant is

How many significant figures are present in $7.964 \times 10^{3}$?

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

The prefix $10^{18}$ is

How many significant figures should be present in the answer of the following calculation? $\frac{2.5 \times 1.25 \times 3.5}{2.01}$