Question

Which of the following is not correct? (a) Nitric oxide in solid state exhibits diamagnetic property. (b) \(\mathrm{NH}_{3}\) is a weak reducing agent compared to \(\mathrm{PH}_{3}\) (c) Hydrolysis of \(\mathrm{NCl}_{3}\) gives \(\mathrm{NH}_{3}\) and \(\mathrm{HOCl}\) (d) \(\mathrm{NH}_{3}\) is less stable than \(\mathrm{PH}_{3}\)

Short answer

The incorrect statement is (d): NH_3 is less stable than PH_3.

Step-by-step solution

Analyzing Statement (a)

Statement (a) asserts that nitric oxide (NO) in solid state exhibits a diamagnetic property. The diamagnetic property means that all electrons are paired. In the solid state, nitric oxide forms a lattice that results in the pairing of the unpaired electron, which makes the substance diamagnetic. Therefore, statement (a) is correct.

Analyzing Statement (b)

Statement (b) claims that ammonia ( ext{NH}_3 ext{)} is a weaker reducing agent compared to phosphine ( ext{PH}_3 ext{)}. Ammonia, due to its higher  ext{N-H} ext{)} bond strength, is indeed a weaker reducing agent than phosphine, which has a more chemically reactive  ext{P-H} ext{)} bond. Thus, statement (b) is correct.

Analyzing Statement (c)

Statement (c) states that the hydrolysis of nitrogen trichloride ( ext{NCl}_3 ext{)} produces ammonia ( ext{NH}_3 ext{)} and hypochlorous acid ( ext{HOCl} ext{)}. This reaction occurs because  ext{NCl}_3 ext{)} reacts with water to release  ext{NH}_3 ext{)} and  ext{HOCl} ext{)} as products. Therefore, statement (c) is correct.

Analyzing Statement (d)

Statement (d) suggests that  ext{NH}_3 ext{)} is less stable than  ext{PH}_3 ext{)}. Ammonia is actually more stable because the  ext{N-H} ext{)} bond is relatively stronger than the  ext{P-H} ext{)} bond, due to greater bond strength and less bond length in  ext{NH}_3 ext{)}. Hence, statement (d) is not correct.

Key concepts

Diamagnetic Property

Diamagnetic substances are fascinating because they are characterized by having all their electrons paired. This unique feature gives them a very distinctive property when they are subjected to a magnetic field. They create an opposing magnetic field, causing them to be repelled by magnets. This is what we refer to as diamagnetic property. Nitric oxide (NO) in solid form exhibits this property.
- In its gaseous form, NO has an unpaired electron and is actually paramagnetic. - However, as it becomes solid, it forms a lattice structure where the unpaired electron becomes paired, showcasing diamagnetism.
It's remarkable how a simple change in state can alter the magnetic properties of a substance dramatically, highlighting the complexity and versatility of nitrogen compounds like nitric oxide.

Reducing Agent

A reducing agent is a substance that donates electrons to another substance during a chemical reaction. This donation leads to the oxidation of the reducing agent. Understanding the strength of reducing agents like ext{NH}_3 (ammonia) and ext{PH}_3 (phosphine) is crucial in chemistry.
- Ammonia is known to be a weaker reducing agent than phosphine. - This is due to the strength of the ext{N-H} bond, which is stronger and less prone to breakage compared to the ext{P-H} bond in phosphine.
Phosphine's propensity to react and donate electrons more readily makes it a stronger reducing agent. Hence, in terms of chemical reactions where reduction is taking place, phosphine is your better bet.

Hydrolysis Reaction

Hydrolysis is an interesting reaction involving water and another compound. In this reaction, a water molecule breaks down another compound. When discussing nitrogen trichloride ( ext{NCl}_3 ), its hydrolysis reaction is quite distinct.
When ext{NCl}_3 reacts with water, it produces ammonia ( ext{NH}_3 ) and hypochlorous acid ( ext{HOCl} ). Here's a simple breakdown:

• ext{NCl}_3 + 3 ext{H}_2 ext{O} → ext{NH}_3 + 3 ext{HOCl}

This reaction highlights the transformative power of hydrolysis, showing how water derivatives can significantly alter the structure and composition of nitrogen compounds.

Chemical Stability

Stability in chemistry refers to how likely a compound is to maintain its form without decomposing or reacting. The stability of nitrogen compounds such as ammonia ( ext{NH}_3 ) versus phosphine ( ext{PH}_3 ) is a telling example.
- Ammonia is generally more stable than phosphine. - This is attributed to the stronger ext{N-H} bonds in ammonia, making it less reactive.
Additionally, the bond length in ammonia is shorter, enhancing its stability compared to phosphine, which has weaker and longer ext{P-H} bonds. Therefore, when predicting reactivity, ammonia's relative stability is a key factor to consider.