Class 12th

(i) Ethanal, Propanal, Propanone, Butanone

The +I effect increases in the order as:

Ethanal

Therefore, the electron density of the carbonyl carbon increases as the +I effect due to the alkyl group increases. As a result, the chances of attack by a nucleophile (which are rich in electrons and carry a negative charge, not necessarily usually have a lone pair of an electrons) decrease because the carbonyl carbon has electron density on it. Hence, the increasing order of the reactivity of the given compounds in nucleophilic addition reaction is:

Ethanal > Propanal> Propanone > Butanone.

(ii) Benzaldehyde, p-Tolualdehyde, p-Nitrobenzaldehyde, Acetophenone:

The +I effect is more in ketone than in aldehyde because in ketone, there are 2 alkyl groups contributing in the +I effect whereas in aldehydes, there is only one alkyl group. Hence, acetophenone (being a ketone group attached to it) is the least reactive in nucleophilic addition reactions.

Among aldehydes, the +I effect is the highest in p-tolualdehyde because of the presence of the electron- donating –CH₃ group (which increase the electron density on the carbonyl carbon via resonance through the benzene ring) and the lowest in p-nitrobenzaldehyde because of the presence of the electron- withdrawing –NO₂ group (which decreases the electron density on the carbonyl carbon via resonance through the benzene ring). Hence, the increasing order of the reactivity of the given compounds is:

Acetophenone<p-tolualdehydep-Nitrobenzaldehyde

The molecular masses of the given compounds are in the range of 44-66 g/mol. The second molecule, CH₃CH₂OH contains OH alcoholic group due to which it undergoes extensive H bonding with each other molecules, leading to the association of the molecules. Therefore, it has the highest boiling point. In the molecule CH₃CHO, there is strong intermolecular dipole-dipole attraction due to presence of - CHO aldehydic group ( as H will have partial positive charge and oxygen will have partial negative charge, so there will attraction between molecules), which is weak in case of CH₃OCH₃ as both CH₃ groups have +I effect which results in decrease in electron affinity for the oxygen attached to it ( with no partially positive H atom). And in CH₃CH₂CH_3, there are only weak van there Waals forces of attraction. So the compounds in increasing order of their boiling point are:

CH₃CH₂CH₃< CH₃OCH₃< CH₃CHO< CH₃CH₂OH.

(i) The compound contains ether group and an aldehydic functional group with the longest chain having 3 carbon atoms. α means the position of the carbon atom attached to attached to the carbon atom of the functional group, in this case, it is an aldehyde functional group.

(ii) The compound contains an alcoholic group and an aldehydic functional group with the longest chain having 4 carbon The numbering of the chain starts from a carbon atom of aldehyde group.

(iii) The compound contains an alcoholic group and an aldehydic functional group, with the longest chain having 5 carbon atoms, which are cyclic in The numbering of the chain starts from a carbon atom of the aldehyde group attached to the cyclopentane ring.

(iv) The compound contains ketone group and an aldehydic functional group with the longest chain having 5 carbon The numbering of the chain starts from a carbon atom of aldehyde group.

(v) The compound contains ketone functional group with the longest chain having 8 (butyl is used because there is two similar butyl group attached to the carbonyl carbon of ketone group) carbon

(vi) The compound contains a fluorine atom and a ketone functional group with the longest chain which is a derivative of a phenyl group and an acetyl substituent.

(i) The compound contains ether group and an aldehydic functional group with the longest chain having 3 carbon atoms. α means the position of the carbon atom attached to attached to the carbon atom of the functional group, in this case, it is an aldehyde functional group.

(ii) The compound contains an alcoholic group and an aldehydic functional group with the longest chain having 4 carbon The numbering of the chain starts from a carbon atom of aldehyde group.

(iii) The compound contains an alcoholic group and an aldehydic functional group, with the longest chain having 5 carbon atoms, which are cyclic in The numbering of the chain starts from a carbon atom of the aldehyde group attached to the cyclopentane ring.

(iv) The compound contains ketone group and an aldehydic functional group with the longest chain having 5 carbon The numbering of the chain starts from a carbon atom of aldehyde group.

(v) The compound contains ketone functional group with the longest chain having 8 (butyl is used because there is two similar butyl group attached to the carbonyl carbon of ketone group) carbon

(vi) The compound contains a fluorine atom and a ketone functional group with the longest chain which is a derivative of a phenyl group and an acetyl substituent.