The S Block Elements

Let's analyze each statement: (a) Alkali metals are strong reducing agents. Alkali metals (Group 1) have one valence electron ( ). They have a strong tendency to lose this electron to form M ions, meaning they are easily oxidized. M M + e Substances that are easily oxidized act as strong reducing agents (they cause other substances to be reduced). Alkali metals have low ionization enthalpies and highly negative standard reduction potentials (e.g., ), indicating their strong reducing nature. So, statement (a) is correct. (b) KO is a diamagnetic oxide. KO is potassium superoxide. The superoxide ion is O . The molecular orbital configuration of O (17 total electrons, or 13 valence electrons if starting from orbitals): . In the antibonding orbitals, there are 3 electrons. This means one orbital is filled with two electrons (paired), and the other orbital has one unpaired electron. For example: . Due to the presence of this one unpaired electron in the O ion, KO is paramagnetic, not diamagnetic. (Diamagnetic substances have all electrons paired). So, statement (b) is incorrect. (c) Lithium chloride exists as LiCl . 2H O Lithium ion (Li ) is very small and has a high charge density. Due to this, it has a high hydration enthalpy and tends to form hydrated salts. Lithium chloride indeed crystallizes from aqueous solution as a hydrate, commonly LiCl 2H O. Other alkali metal chlorides (NaCl, KCl, etc.) are generally anhydrous because their cations are larger and have lower charge densities, thus weaker hydration tendencies. So, statement (c) is correct. Based on the analysis: Statement (a) is correct. Statement (b) is incorrect. Statement (c) is correct. Therefore, the correct statements are (a) and (c). This corresponds to option (b).

Let’s verify each statement:
- I. False – Lithium hydrogen carbonate (LiHCO ) is unstable and does not exist as a solid.
- II. True – LiCl is covalent enough to dissolve in ethanol.
- III. False – Lithium oxide has the formula Li O, not LiO.
- IV. True – Lithium hydroxide decomposes on heating to give lithium oxide and water.

Step 1: Evaluate each statement. \begin{itemize} \item (1) Cesium forms superoxide (O ): Alkali metals react with oxygen to form oxides, peroxides, or superoxides. Cesium, due to its large size and low ionization energy, primarily forms the superoxide (CsO ). This statement is correct. \item (2) Sodium peroxide (Na O ) is paramagnetic: The peroxide ion (O ) has a bond order of 1 and all its electrons are paired. Therefore, sodium peroxide is diamagnetic, not paramagnetic. This statement is incorrect. \item (3) Lithium chloride (LiCl) is deliquescent: Deliquescent substances absorb moisture from the air to such an extent that they dissolve in the absorbed water to form a saturated solution. Lithium chloride is known to be deliquescent due to the high polarizing power of the small Li ion, which strongly attracts water molecules. This statement is correct. \item (4) White metal is an alloy of lithium and lead: White metal is a tin-based alloy containing copper and antimony. It is not an alloy of lithium and lead. This statement is incorrect. \end{itemize}
Step 2: Identify the incorrect statement.
Statements (2) and (4) are incorrect. However, only one incorrect statement is expected as the answer. Reviewing the provided correct answer indicates that statement (2) is considered the incorrect one. Final Answer:

Statement I: BeSO and MgSO are readily soluble in water due to the high hydration enthalpy of the smaller Be and Mg ions, which overcomes their lattice enthalpy. This statement is correct. Statement II: All nitrates of alkaline earth metals decompose on heating to give their corresponding oxides, NO , and O . So, this statement is incorrect. It's not exclusive to Be(NO ) .