Question

Correct statements from the following are:
A. Nitrogen in oxidation states from \(+1\) to \(+4\) disproportionates in acid medium.
B. Nitrogen has the ability to form \(d\pi - p\pi\) multiple bonds with itself and other elements with small size and high electronegativity.
C. N-N single bond is stronger than P-P single bond.
D. Nitrogen has highest density in its group due to small size.
E. The maximum covalency of nitrogen is four since it has only four valence orbitals for bonding.

• A. B, C and D Only
• B. C, D and E Only
• C. A, C and E Only
• D. A and E Only

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The topic is the Chemistry of p-Block Elements, specifically focusing on the properties of Nitrogen (Group 15). We must identify the correct statements among the given options.
Step 2: Detailed Explanation:
Statement A: This is correct. In acidic solutions, nitrogen species with intermediate oxidation states (like \(HNO_2\), \(+3\)) are unstable and undergo disproportionation, where the same element is both oxidized and reduced (e.g., \(3HNO_2 \to HNO_3 + 2NO + H_2O\)).
Statement B: This is incorrect. Nitrogen is in the second period and lacks d-orbitals in its valence shell. It can only form \(p\pi - p\pi\) multiple bonds, not \(d\pi - p\pi\) bonds. Heavier elements in the group like phosphorus can form \(d\pi - p\pi\) bonds.
Statement C: This is incorrect. The N-N single bond (bond energy \(\approx 160\) kJ/mol) is significantly weaker than the P-P single bond (\(\approx 200\) kJ/mol). This is due to the small size of the nitrogen atom, which leads to strong inter-electronic repulsion between the lone pairs on adjacent nitrogen atoms.
Statement D: This is incorrect. Density generally increases down a group due to the increasing atomic mass outweighing the increase in atomic volume. Nitrogen, as the first element of Group 15, has the lowest density.
Statement E: This is correct. Nitrogen's valence shell is \(n=2\), which contains one \(2s\) and three \(2p\) orbitals, for a total of four orbitals. It cannot expand its octet, thus its maximum covalency is limited to four (as seen in the ammonium ion, \(NH_4^+\)).
Therefore, only statements A and E are correct.
Step 3: Final Answer:
The correct statements are A and E Only.