In Avogadro’s constant $6.022 \times {10}^{23} {\mathrm{mol}}^{-1}$, the number of significant figures is _____.

By decomposition of $25 \mathrm{g}$ of ${\mathrm{CaCO}}_3$ , the amount of $\mathrm{CaO}$ produced will be _____

How many grams of water will be produced by complete combustion of $12 \mathrm{g}$ of methane gas

Two elements $\mathrm{A}$ (Atomic mass $75$) and $\mathrm{B}$ (Atomic mass $16$) combine to give a compound having $75.8 \%$ of $\mathrm{A}$. The formula of the compound is

In${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$ the percentage of water is _____ $(\mathrm{Cu} = 63.5, \mathrm{S} = 32, \mathrm{O} = 16, \mathrm{H} = 1)$.

When two properties of a system are mathematically related to each other, the relation can be deduced by

Define least count.