Understanding the Concept:
Chemical species are categorized based on their electron density preferences:
Electrophiles are electron-deficient species (Lewis acids) that accept an electron pair. They can be positively charged ($\text{NO}_2^+$) or neutral molecules with vacant valence shells ($\text{AlCl}_3$, $\text{SO}_3$).
Nucleophiles are electron-rich species (Lewis bases) that carry a lone pair of electrons or a negative charge ($\text{NH}_3$, $\text{H}_2\text{O}$, $\text{CN}^-$) available to donate into an electron-deficient center.
Step 1: Evaluate Statement (D).
Statement (D) includes Ammonia ($\text{NH}_3$) and Water ($\text{H}_2\text{O}$) in a list of electrophiles. Both ammonia and water have non-bonding lone pairs on their central heteroatoms ($\ddot{\text{N}}\text{H}_3$ and $\text{H}_2\ddot{\text{O}}$:), which allows them to readily donate electron pairs. This means they function as nucleophiles, not electrophiles. Therefore, statement (D) contains an incorrect classification, making it the correct choice for this question.
Step 2: Verify why the other options are correct statements.
Statement (A) is a valid chemical fact: The sodium nitroprusside test for sulfur forms a characteristic violet-colored coordination complex via the reaction: $\text{Na}_2[\text{Fe}(\text{CN})_5\text{NO}] + \text{Na}_2\text{S} \rightarrow \text{Na}_4[\text{Fe}(\text{CN})_5\text{NOS}]$.
Statement (B) is a valid practical fact: Methanol (b.p. $64.7^\circ\text{C}$) and acetone (b.p. $56^\circ\text{C}$) have close boiling points, meaning fractional distillation is required to separate them cleanly.