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# Which of the following is not true about Phosphine?

(1) It has an unpleasant odour like rotten fish

(2) It precipitates out of metals from their aqueous salt solutions as metallic phosphates

(3) It burns in air or oxygen giving phosphorus trixoide and water

(4) It cannot be prepared by heating phosphorus acid

(5) Phosphine is an ionic molecule

$\begin{array}{1 1} (3), (4) and (5) are all incorrect \\Both (3) and (5) are incorrect \\ Both (4) and (5) are incorrect \\ Both (3) and (4) are incorrect \end{array}$

Answer: (3), (4) and (5) are all incorrect
(3) It burns in air or oxygen giving phosphorus trixoide and water $\rightarrow$ it burns in air giving phosphorus pentoxide and water as follows:
$\quad \quad 2\text{PH}_3 + 4\text{O}_2 \rightarrow \text{P}_2\text{O}_5 + 3\text{H}_2\text{O}$
(4) It cannot be prepared by heating phosphorus acid $\rightarrow$ infact, it can be prepared by heating phosphorus acid at $210^{\circ}$
$\quad\quad 4\text{H}_3\text{PO}_3 \xrightarrow[]{heat} \text{PH}_3 + \text{H}_3\text{PO}_4$
(5) Phosphine is an ionic molecule $\rightarrow$ bonds are covalent because phosphorus and hydrogen are both non-metals, non-metals form a covalent bond
Statements (1) and (2) are correct.

–1 vote