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 very strong crystalline lattice. In the light of the above statements, choose the most appropriate answer from the options given below ;

Both (A) and (R) are correct and (R) is the correct explanation of (A)

Both (A) and (R) are correct but (R) Is not the correct explanation of (A)

P Block Elements PYQ — JEE Main 2024 · 27 Jan · Shift 1 · Q13 with Solution

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Correct answer: B

Evaluate Assertion (A)

Assertion: Melting point of Boron $(2453\,\text{K})$ is unusually high in group 13 elements.

In group 13, boron has a much higher melting point than the other elements like Al, Ga, In, and Tl. This is a well-known anomaly of boron.

Hence, Assertion (A) is true.
Evaluate Reason (R)

Reason: Solid Boron has very strong crystalline lattice.

Boron exists as a hard solid with a covalent network structure and very strong bonding in its crystalline lattice. Because of these strong bonds, a large amount of energy is needed to melt it.

Hence, Reason (R) is true.
Check whether (R) explains (A)

The unusually high melting point of boron is due to its very strong crystalline/covalent network lattice. Therefore, the reason directly explains the assertion.
Conclusion
- (A) is true
- (R) is true
- (R) is the correct explanation of (A)
Therefore, the correct option is B.

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Correct answer: B

Evaluate Assertion (A)

Assertion: Melting point of Boron $(2453\,\text{K})$ is unusually high in group 13 elements.

In group 13, boron has a much higher melting point than the other elements like Al, Ga, In, and Tl. This is a well-known anomaly of boron.

Hence, Assertion (A) is true.
Evaluate Reason (R)

Reason: Solid Boron has very strong crystalline lattice.

Boron exists as a hard solid with a covalent network structure and very strong bonding in its crystalline lattice. Because of these strong bonds, a large amount of energy is needed to melt it.

Hence, Reason (R) is true.
Check whether (R) explains (A)

The unusually high melting point of boron is due to its very strong crystalline/covalent network lattice. Therefore, the reason directly explains the assertion.
Conclusion
- (A) is true
- (R) is true
- (R) is the correct explanation of (A)
Therefore, the correct option is B.