Correct Option
The correct option is (b).
Explanation
The chemical properties of elements, such as valency and group placement, are determined by their electronic configuration. Elements in the same group of the periodic table share the same number of valence electrons, which influences their bonding behavior.
Statement-wise Analysis
- Statement 1 is Incorrect. Nitrogen (Atomic Number 7) has the electronic configuration \(1s^2 2s^2 2p^3\). It has 5 valence electrons in its outermost shell, not 3. Furthermore, while Nitrogen can exhibit an oxidation state of +5, it cannot exhibit a covalency (valency) of 5 because it lacks d-orbitals in its valence shell to expand its octet. Its maximum covalency is 4 (e.g., in \(NH_4^+\)).
- Statement 2 is Correct. Phosphorus (Atomic Number 15) has the electronic configuration \([Ne] 3s^2 3p^3\). It possesses 5 valence electrons. Unlike Nitrogen, Phosphorus has empty d-orbitals in its valence shell, allowing it to expand its octet. Therefore, it can exhibit a valency of 3 (e.g., \(PCl_3\)) as well as a valency of 5 (e.g., \(PCl_5\)).
- Statement 3 is Incorrect. Nitrogen and Phosphorus belong to the same group, which is Group 15 (the Nitrogen family or Pnictogens) of the Modern Periodic Table. They are chemically similar in terms of valence shell configuration (\(ns^2 np^3\)).
Key Takeaway
Nitrogen is restricted to a maximum covalency of 4 due to the absence of d-orbitals, whereas Phosphorus (and heavier Group 15 elements) can expand its valency to 5 due to the availability of vacant d-orbitals.