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MHTCET 20 Apr 2026 Shift 1 Paper

Question : 66 of 150

Marks: +1, -0

Which from following is a correct priority order for selection of principal functional group for nomenclature of polyfunctional compound according to IUPAC system ?

$-\mathrm{CHO} > -\mathrm{CONH}_{2} > -\mathrm{OH} > -C \equiv C-$
$-\mathrm{CONH}_{2} > -\mathrm{CHO} > -\mathrm{OH} > -C \equiv C-$
$-C \equiv C- > -\mathrm{OH} > -\mathrm{CONH}_{2} > -\mathrm{CHO}$
$-C \equiv C- > -\mathrm{CHO} > -\mathrm{CONH}_{2} > -\mathrm{OH}$

Validate

Solution:

Concept:

For polyfunctional compounds, the IUPAC system selects the principal functional group based on a fixed priority order; the group with the highest priority determines the suffix in the name.

Explanation:

According to IUPAC nomenclature, the decreasing order of priority for the given groups is: amide (

-\mathrm{CONH}_{2}

) > aldehyde (

-\mathrm{CHO}

) > alcohol (

-\mathrm{OH}

) > alkyne (

-C \equiv C-

Amides have the highest priority, so they are chosen as the principal functional group and are indicated by the suffix "-amide".

Aldehydes rank next and are designated by the suffix "-al".

Alcohols have lower priority and are denoted by the suffix "-ol".

Alkynes (triple bonds) have the lowest priority among these and are treated as substituents with the prefix "alkynyl" when a higher-priority group is present.

Thus, the correct sequence is

-\mathrm{CONH}_{2} > -\mathrm{CHO} > -\mathrm{OH} > -C \equiv C-

Answer:

Option B:

-\mathrm{CONH}_{2} > -\mathrm{CHO} > -\mathrm{OH} > -C \equiv C-

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