Question

How would you name the following compounds? (i) ${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{Br}$ (ii) $\mathrm{H}-\mathrm{CHO}$ (ii) ${\mathrm{CH}}_3-{\left({\mathrm{CH}}_2\right)}_3-\mathrm{CH}={\mathrm{CH}}_2$

• A. (i) Bromomethane (ii) Methanol (iii) Hexene
• B. (i) Bromoethane (ii) Ethanol (iii) Hexene
• C. (i) Bromopropane (ii) Methanol (iii) Hexene
• D. (i) Bromoethane (ii) Methanal (iii) Hexene

Answer 1

The correct option is D

(i) Bromoethane (ii) Methanal (iii) Hexene

Explanation for Correct Option:

Option (D): (i) Bromoethane (ii) Methanal (iii) Hexene

• From the given compounds, ${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{Br}$ is Bromoethane, $\mathrm{H}-\mathrm{CHO}$ is Methanal and ${\mathrm{CH}}_3-{\left({\mathrm{CH}}_2\right)}_3-\mathrm{CH}={\mathrm{CH}}_2$ is Hexene.
• In $\mathrm{H}-\mathrm{CHO}$, there is only 1 carbon atom and also there is an aldehyde group$(-\mathrm{CHO})$ present, hence its name is Methanal.
• Hence it is the correct option.

Explanation for Incorrect Option:

Option (A): (i) Bromomethane (ii) Methanol (iii) Hexene

• In this option it is given that $\mathrm{H}-\mathrm{CHO}$ is Methanol.
• This is incorrect because, in Methanol, there is 1 carbon atom and an alcohol group$(\mathrm{R}-\mathrm{OH})$.
• Structure of Methanol is ${\mathrm{CH}}_3-\mathrm{OH}$ not $\mathrm{H}-\mathrm{CHO}$.
• Hence it is the incorrect option

Option (B): (i) Bromoethane (ii) Ethanol (iii) Hexene

• In this option, we have been given that $\mathrm{H}-\mathrm{CHO}$ is Ethanol.
• This is not possible as, in Ethanol, there are 2 carbon atoms and also an alcohol group is present$(\mathrm{R}-\mathrm{OH})$.
• The structure of Ethanol is ${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{OH}$ not $\mathrm{H}-\mathrm{CHO}$.
• Hence it is the incorrect option.

Option (C): (i) Bromopropane (ii) Methanol (iii) Hexene

• Here in this option, $\mathrm{H}-\mathrm{CHO}$ ha been written as Methanol.
• This is not true because, in Methanol, there is an alcohol group$(\mathrm{R}-\mathrm{OH})$ present.
• But here the compound has an Aldehyde group$(-\mathrm{CHO})$ present in it.
• thus its name is Methanal not Methanol.
• Hence it is the incorrect option.

Therefore, the names of the compounds (i) ${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{Br}$ (ii) $\mathrm{H}-\mathrm{CHO}$ (ii) ${\mathrm{CH}}_3-{\left({\mathrm{CH}}_2\right)}_3-\mathrm{CH}={\mathrm{CH}}_2$ are option (D) (i) Bromoethane (ii) Methanal (iii) Hexene