Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R) Assertion (A): Boron is unable to form \(\mathrm{BF}_{6}^{3-}\) Reason (R): Size of B is very small. In the light of the above statements, choose the correct answer from the options given below:

(B) Both (A) and (R) are true but (R) is not the correct explanation of (A)

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

(C) (A) is true but (R) is false

(D) (A) is false but (R) is true

JEE Main · 2022 · 27 Jul 2022 · Shift 2 · p-Block Elements

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R)

Assertion (A): Boron is unable to form

BF_{6}^{3 -}

Reason (R): Size of B is very small.
In the light of the above statements, choose the correct answer from the options given below:

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

Answer: (B)

Solution

Assertion (A) is true: Boron cannot form

BF_{6}^{3 -}

because it lacks d-orbitals and cannot expand its octet beyond 8 electrons. The maximum coordination number for boron is 4.

Reason (R) is true: The size of boron is indeed very small.

However, (R) is not the correct explanation of (A). The inability to form

BF_{6}^{3 -}

is primarily due to the absence of vacant d-orbitals for octet expansion, not just the small size. Small size would actually favor higher coordination if d-orbitals were available.

Therefore, both statements are true but (R) is not the correct explanation of (A).

JEE Main · 2022 · 27 Jul 2022 · Shift 2 · Single correct option

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JEE Main · 2022 · 27 Jul 2022 · Shift 2 · p-Block Elements

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