Chemistry · p-Block (I) (Grp. 13, 14)
JEE Main 2024 — 27 January, Shift 1 — Question 66
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 ;
- Option A:Correct
Both (A) and (R) are true and (R) is the correct explanation of (A).
- Option B:
Both (A) and (R) are true but (R) Is not the correct explanation of (A).
- Option C:
(A) is true but (R) is false
- Option D:
(A) is false but (R) is true
Answer: A
Step-by-step solution
Assertion (A) is true: Boron has an unusually high melting point (2453 K) compared to other group 13 elements such as Al, Ga, In and Tl.
Reason (R) is true and explains (A): Solid boron possesses a giant covalent (network) crystalline lattice with very strong B–B covalent bonds. A large amount of energy is required to break this rigid lattice, resulting in a high melting point.
Thus, both Assertion and Reason are true, and Reason is the correct explanation of Assertion → Option A.
Answer key and solution verified before publishing.
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- Exam
- JEE Main 2024
- Paper
- 27 January, Shift 1
- Subject
- Chemistry
- Chapter
- p-Block (I) (Grp. 13, 14)
- Topic
- Introduction & Properties of Group 13: Boron Family