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 address this question, both the Assertion (A) and Reason (R) require evaluation.

Assertion (A): Boron's melting point (2453 K) is exceptionally high among group 13 elements.

Reason (R): Solid Boron exhibits an extremely robust crystalline lattice.

1. Evaluate Assertion (A): Boron's melting point is notably higher than other group 13 elements like aluminum, gallium, indium, and thallium. Consequently, Assertion (A) is accurate.
2. Evaluate Reason (R): Boron forms a highly robust and intricate three-dimensional covalent network, resulting in a strong crystalline lattice. This structure is the primary cause of its elevated melting point. Therefore, Reason (R) is also accurate.
3. Determine the explanatory relationship: The formidable covalent lattice of boron is directly responsible for its high melting point, as breaking this extensive network of bonds demands substantial energy. Thus, Reason (R) correctly explains Assertion (A).

Based on this analysis, both the assertion and the reason are correct, and the reason accurately elucidates the assertion.

The definitive conclusion is: Both (A) and (R) are correct, and (R) provides the correct explanation for (A).