(A): The bond dissociation energy of fluorine is less than bromine.
(R): In fluorine molecule, large lone pair electronic repulsions and appreciable internuclear repulsions are present.

Options

A. Both A & R are true, R is the correct explanation of A
B. Both A & R are true, R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true

Answer

To analyze the given statements about the bond dissociation energy of fluorine and bromine, we will break down the problem step by step.

### Step 1: Understanding Bond Dissociation Energy
Bond dissociation energy is the energy required to break a bond between two atoms in a molecule. A higher bond dissociation energy indicates a stronger bond.

### Step 2: Comparing Fluorine and Bromine
The question states that the bond dissociation energy of fluorine (F2) is less than that of bromine (Br2). This means that the bond in F2 is weaker than the bond in Br2.

### Step 3: Analyzing the Structure of Fluorine Molecule
In the fluorine molecule (F2), each fluorine atom has three lone pairs of electrons. The presence of these lone pairs leads to significant electron-electron repulsion.

### Step 4: Effects of Lone Pair Repulsion
Due to the small size of the fluorine atom, the lone pairs are relatively close to each other, which increases the repulsion between them. This repulsion destabilizes the bond, making it weaker.

### Step 5: Comparing with Bromine
In bromine (Br2), although there are also lone pairs, the larger size of bromine atoms means that the lone pairs are farther apart compared to those in fluorine. This results in less repulsion and a stronger bond in Br2.

### Step 6: Conclusion
Thus, the bond dissociation energy of fluorine is indeed less than that of bromine due to the significant lone pair repulsion in fluorine.

### Step 7: Evaluating the Reasoning
The reasoning provided states that in the fluorine molecule, there are large lone pair electronic repulsions and appreciable internuclear repulsions present. This statement is true and serves as a correct explanation for why the bond dissociation energy of fluorine is lower than that of bromine.

### Final Answer
Both statements (A) and (R) are true, and (R) is the correct explanation of (A).

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