MCQ
Phosphorus normally exhibits a covalency of:
  • $+3$ and $+5$
  • B
    $+2$ and $+3$
  • C
    $+1$ and $+2$
  • D
    $+3$ and $+4$

Answer

Correct option: A.
$+3$ and $+5$
Phosphorous acid $\ce{H_3PO_3},$ metaphosphorous acid $\ce{HPO_2}$​ has $+3$ oxidation state.
Pyrophosphoric acid $\ce{H_4P_2O_7}$​, orthophosphoric acid $\ce{H_3PO_4}$​ has $+5$ oxidation state.

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($1$)The number of heteroatoms present in one molecule of $R$ is. . . . .  .

[Use: Molar mass (in g mol ${ }^{-1}$ ): $\mathrm{H}=1, \mathrm{C}=12, \mathrm{~N}=14, \mathrm{O}=16, \mathrm{Br}=80, \mathrm{Cl}=35.5$

Atoms other than $\mathrm{C}$ and $\mathrm{H}$ are considered as heteroatoms]

($2$)The total number of carbon atoms and heteroatoms present in one molecule of $S$. . . . . .

[Use: Molar mass in $\mathrm{g} \mathrm{mol}^{-1}$ ]: $\mathrm{H}=1, \mathrm{C}=12, \mathrm{~N}=14, \mathrm{O}=16, \mathrm{Br}=80, \mathrm{Cl}=35.5$

Atoms other than $\mathrm{C}$ and $\mathrm{H}$ are considered as heteroatoms

Give the answer quetion ($1$) and ($2$)