Question

Pure acetylene has sweet smell, whereas impure gives garlic odour due to presence of:
A) ${\text{N}}{{\text{H}}_{\text{3}}}$
B) ${\text{P}}{{\text{H}}_{\text{3}}}$
C) ${\text{Sb}}{{\text{H}}_{\text{3}}}$
D) ${\text{HCl}}$

Answer 1

In organic chemistry, hydrocarbons are an important topic. The hydrocarbons are majorly classified as three groups. There are alkane, alkene and alkyne. The alkane means carbon-carbon single bond. The alkene has a carbon-carbon double bond. The alkyne means carbon-carbon having triple bond in the molecule. It has some general formulas. The general formula of alkane is${{\text{C}}_{\text{n}}}{{\text{H}}_{{\text{2n + 2}}}}$. The general formula of alkene is${{\text{C}}_{\text{n}}}{{\text{H}}_{{\text{2n}}}}$. The general formula of alkyne is ${{\text{C}}_{\text{n}}}{{\text{H}}_{{\text{2n - 2}}}}$.

Complete answer:
Pure acetylene has a sweet smell, whereas impure gives garlic odour due to the presence of phosphine.
According to the above discussion, we conclude pure acetylene has sweet smell, whereas impure gives garlic odour due to presence of phosphine ${\text{P}}{{\text{H}}_{\text{3}}}$.
Therefore,
Option A is not correct, because pure acetylene has sweet smell, whereas impure gives garlic odour is not due to${\text{N}}{{\text{H}}_{\text{3}}}$.
Option C is not correct, because pure acetylene has sweet smell, whereas impure gives garlic odour is not due to${\text{Sb}}{{\text{H}}_{\text{3}}}$.
Option D is not correct, because pure acetylene has a sweet smell, whereas impure garlic odour is not due to ${\text{HCl}}$.

Hence,Option B is correct, because pure acetylene has sweet smell, whereas impure gives garlic odour due to presence of ${\text{P}}{{\text{H}}_{\text{3}}}$.

Note:
We have to know that the molecular formula of acetylene is ${{\text{C}}_2}{{\text{H}}_{\text{2}}}$. Acetylene is one of the alkyne. The molecular formula of phosphine is ${\text{P}}{{\text{H}}_{\text{3}}}$. The molecular formula of ammonia is${\text{N}}{{\text{H}}_{\text{3}}}$. The molecular formula of hydrochloric acid is ${\text{HCl}}$. The molecular formula of antimony hydride is${\text{Sb}}{{\text{H}}_{\text{3}}}$. Acetylene is one of the unsaturated hydrocarbons. Acetylene is one of the triple bond molecules. Acetylene is the first alkyne compound.