Statement I: Nucleophilic substitution of iodoethane is easier than chloroethane

Statement II: Bond energy of C–I bond is less than that of C–Cl bond

Both statement I and statement II are correct and statement II is the correct explanation of statement I

The correct answer is option 1. Both statement I and statement II are correct and statement II is the correct explanation of statement I.

Statement I is correct because the C-I bond is weaker than the C-Cl bond. This means that it is easier to break the C-I bond, which makes the nucleophilic substitution of iodoethane easier than chloroethane.

Statement II is also correct because the bond energy of a bond is one of the factors that determines the ease of nucleophilic substitution. The lower the bond energy, the easier it is to break the bond, and the easier it is for nucleophilic substitution to occur.

Therefore, both statements I and II are correct and statement II is the correct explanation of statement I.

Here is a table that summarizes the bond energies of the C-X bonds:

As you can see, the bond energy of the C-I bond is the lowest of all the halogens, which means that it is the easiest to break. This makes nucleophilic substitution of iodoethane easier than chloroethane, as stated in statement I.

In conclusion, the ease of nucleophilic substitution of iodoethane is determined by the bond energy of the C-I bond. The lower the bond energy, the easier it is to break the bond, and the easier it is for nucleophilic substitution to occur.