Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Melting point of Boron (2453 K) is unusually high in group 13 elements.
Reason (R): Solid Boron has a very strong crystalline lattice. 
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
• B. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• C. (A) is true but (R) is false
• D. (A) is false but (R) is true

Answer 1

The Correct Option is B

To solve this problem, we need to evaluate both the Assertion (A) and Reason (R) given in the question. 

Assertion (A): Melting point of Boron (2453 K) is unusually high in group 13 elements.

Reason (R): Solid Boron has a very strong crystalline lattice.

1. First, let's examine the Assertion (A). Boron's melting point is indeed significantly higher compared to other group 13 elements, such as aluminum, gallium, indium, and thallium. This makes Assertion (A) a true statement.
2. Next, let's consider the Reason (R). Boron does form a very strong and complex three-dimensional covalent network structure, leading to a strong crystalline lattice. This crystalline structure is primarily responsible for its high melting point. Hence, Reason (R) is also a true statement.
3. Now, we need to determine if Reason (R) is the correct explanation for Assertion (A). The strong covalent lattice of boron contributes to its high melting point because breaking this extensive network of bonds requires a significant amount of energy. Therefore, Reason (R) indeed serves as a proper explanation for Assertion (A).

Given this logical analysis, both the assertion and the reason are correct, and the reason correctly explains the assertion.

The correct answer is: Both (A) and (R) are correct and (R) is the correct explanation of (A).

Answer 2

Both Assertion (A) and Reason (R) are correct, and (R) explains (A). Boron has a strong crystalline structure due to covalent bonding and a unique lattice arrangement, which leads to its unusually high melting point within group 13 elements.