In each of the following question, a statement of Assertion (A) is given followed by a corresponding statement of Reason (R). Choose the correct answer as:

Assertion (A): NF₃ is a weak ligand than N(CH₃)₃.

Reason (R):  NF₃ ionizes to give F^– ion in aqueous solution.

If the assertion is true, but the reason is false

The correct answer is option 3. If the assertion is true, but the reason is false.

Let us break down the assertion and reason provided:

Assertion: \(NF_3\) is a weaker ligand than \(N(CH_3)_3\)

This assertion is true. In coordination chemistry, the term "ligand" refers to a molecule or ion that can donate a pair of electrons to form a coordinate bond with a central metal ion. The strength of a ligand is often determined by its ability to donate electron pairs effectively. In general, ligands with more available lone pairs tend to be stronger ligands. \(NF_3\) (nitrogen trifluoride) is considered a weaker ligand compared to \(N(CH_3)_3\) (trimethylamine) because nitrogen in NF3 has fewer available lone pairs for donation compared to nitrogen in \(N(CH_3)_3\).

Reason: \(NF_3\) ionizes to give \(F^–\) ion in aqueous solution

This reason is false. \(NF_3\) does not ionize to give fluoride ions \((F^–)\) in aqueous solution. Instead, \(NF_3\) acts as a Lewis base by donating a lone pair of electrons to form coordinate bonds with metal ions. The ionization behavior described in the reason does not apply to \(NF_3\).

In summary, while the assertion about \(NF_3\) being a weaker ligand than \(N(CH_3)_3\) is true, the reason provided to support it is false. \(NF_3\)'s weaker ligand strength is attributed to its lesser availability of lone pairs for donation compared to \(N(CH_3)_3\). Therefore, the correct answer is that the assertion is true, but the reason is false.