Question

The decreasing order of reactivity of the following organic molecules towards the ${\mathrm{AgNO}}_3$ solution is

• A. $\left(\mathrm{B}\right)>\left(\mathrm{A}\right)>\left(\mathrm{C}\right)>\left(\mathrm{D}\right)$
• B. $\left(\mathrm{A}\right)>\left(\mathrm{B}\right)>\left(\mathrm{C}\right)>\left(\mathrm{D}\right)$
• C. $\left(\mathrm{A}\right)>\left(\mathrm{B}\right)>\left(\mathrm{D}\right)>\left(\mathrm{C}\right)$
• D. $\left(\mathrm{C}\right)>\left(\mathrm{D}\right)>\left(\mathrm{A}\right)>\left(\mathrm{B}\right)$

Answer 1

The correct option is A

$\left(\mathrm{B}\right)>\left(\mathrm{A}\right)>\left(\mathrm{C}\right)>\left(\mathrm{D}\right)$

The explanation for the correct option:

Option (A): $\left(\mathrm{B}\right)>\left(\mathrm{A}\right)>\left(\mathrm{C}\right)>\left(\mathrm{D}\right)$

1. Reactivity towards ${\mathrm{AgNO}}_3$ is decided by the stability of the cation formed. The more the stability of a cation, the more reactive it is.
2. The Compound A forms an aromatic carbocation as it is cyclic in nature, carbocation is ${\mathrm{sp}}^2$ hybridized and it follows huckle's rule
3. The compound B is also aromatic with a methoxy group attached which increases its stability
4. compound C forms a secondary carbocation after removal of the chlorine group.
5. The compound D also forms a secondary carbocation but with the presence of the -I group, its stability decreases.
6. Order of stability of carbocations is $\left(\mathrm{B}\right)>\left(\mathrm{A}\right)>\left(\mathrm{C}\right)>\left(\mathrm{D}\right)$
7. Hence, it is the correct option.

The explanation for the incorrect options:

Option (B): $\left(\mathrm{A}\right)>\left(\mathrm{B}\right)>\left(\mathrm{C}\right)>\left(\mathrm{D}\right)$

1. Compound B is aromatic with a methoxy group attached which increases its stability more than compound A.
2. Hence, it is an incorrect option.

Option (C): $\left(\mathrm{A}\right)>\left(\mathrm{B}\right)>\left(\mathrm{D}\right)>\left(\mathrm{C}\right)$

1. The compound D also forms a secondary carbocation but with the presence Of the -I group, its stability decreases. hence making it least reactive
2. Hence, it is an incorrect option

Option (D): $\left(\mathrm{C}\right)>\left(\mathrm{D}\right)>\left(\mathrm{A}\right)>\left(\mathrm{B}\right)$

1. Compound B is aromatic with a methoxy group attached which increases its stability more than compound A.
2. Hence, it is an incorrect option.

Therefore, the decreasing order of reactivity of the organic molecules towards the ${\mathrm{AgNO}}_3$ solution is $\left(\mathrm{B}\right)>\left(\mathrm{A}\right)>\left(\mathrm{C}\right)>\left(\mathrm{D}\right)$