Question

Select the set of the substituent groups which exert -M and negative inductive effects:
 $$\begin{gathered} A)-CC{l}_3,-COOH,-CN \\ B)-C{H}_3,-Cl,-F \\ C)-S{O}_{3}H,-OC{H}_3,-CHO \\ D)-N{O}_2,-COCl,-N{H}_2 \end{gathered}$$

Answer 1

Hint : To answer this question, we first need to understand what inductive effect is. The inductive effect is a chemical term for the transfer of uneven bonding electron sharing through a chain of atoms in a molecule, resulting in a permanent dipole in a bond. It exists in a bond, as opposed to the electromeric effect, which also exists in a bond.

Complete Step By Step Answer:
Mesomeric effect - The Mesomeric effect is the polarity created between atoms of a conjugated system via electron transfer or pi–bond electron transfer. In simple words, the mesomeric effect happens when electrons in a conjugated orbital system move away from or towards a substituent group.
Two types of mesomeric effects can be distinguished:
-M effect – The negative mesomeric (–M) effect occurs when pi-bond electrons are moved from the conjugate system to a specific group, resulting in a drop in the conjugate system's electron density. The group must have either a positive charge or a vacant orbital for the –M effect to occur. The –M effect makes a molecule more reactive to a nucleophile by lowering the electron density in the conjugate system, but also makes it less reactive to an electrophile for the same reasons.
The group which shows –M effect include;
 $-N{O}_2,-CN,-COX,-S{O}_{3}H,-CHO,-CON{H}_2,-COR,-COOH,-COORetc.$
+M effect - The (+M) effect or positive mesomeric effect occurs when electrons or pi electrons are moved from a specific group to a conjugate system, thereby boosting the electron density of the conjugated system. The group must have either a lone pair of electrons or a negative charge to produce the +M effect. The +M effect causes the conjugate system to have a negative charge, or the electron density to increase on the conjugate system. These conjugate complexes have a higher electrophile reactivity and a lower nucleophile reactivity.
Group showing +M effect
 $-NH,-N{H}_2,-NHR,-N{R}_2,-O,-OH,-OR,-F,-Cl,-O-COR,-NHCOR,-SH,-SRetc.$
So, we can conclude that $-N{O}_2,-COCl,-N{H}_2$ exert -M and negative inductive effects
So, the final answer is option (D) i.e. $-N{O}_2,-COCl,-N{H}_2$ .

Note :
The resonance effect occurs when two or more distinct structures for the same molecule or ion can be drawn that have the same arrangement of atomic nuclei but differ in the distribution of electrons. Contributing or resonant structures are the many structures. The single resonating structure does not show all of the features of the molecule or ion, but the true structure is a resonance hybrid of all the resonating structures.