Which diagram represents the lattice structure of sodium chloride?
Correct Answer: \( \boxed{\mathrm{B}} \)
Sodium chloride has a giant ionic lattice consisting of alternating \( \mathrm{Na^+} \) and \( \mathrm{Cl^-} \) ions.
Each sodium ion is surrounded by chloride ions, and each chloride ion is surrounded by sodium ions. The ions are arranged in a regular repeating pattern.
Diagram B correctly shows alternating positive and negative ions in the lattice.
Diagram A shows neutral atoms instead of ions, diagram C has the ions incorrectly labelled, and diagram D does not represent the regular ionic lattice of sodium chloride.
Therefore, the correct answer is (B).
Information about two substances is given.
| Substance | Electrical conductivity | Effect of adding to water | Melting point / K |
|---|---|---|---|
| P | Good when solid and when molten | Reacts vigorously to produce an alkaline solution | 454 |
| Q | Does not conduct in any state | Reacts vigorously to produce an acidic solution | 317 |
Which row describes the structure and bonding in substances P and Q?
| P | Q | |
|---|---|---|
| (A) | Giant metallic | Simple molecular |
| (B) | Simple molecular | Giant metallic |
| (C) | Giant ionic | Simple molecular |
| (D) | Giant metallic | Giant ionic |
Correct Answer: \( \boxed{\mathrm{A}} \)
Substance P conducts electricity in both the solid and molten states, indicating the presence of delocalised electrons. It also reacts vigorously with water to form an alkaline solution, a characteristic property of reactive metals. Therefore, P has a giant metallic structure.
Substance Q does not conduct electricity in any state and reacts with water to produce an acidic solution. Its relatively low melting point also indicates a simple molecular substance.
Therefore, the correct answer is (A).
Phosphorus forms a compound with hydrogen called phosphine, PH₃. This compound can react with a hydrogen ion, H⁺. Which type of interaction occurs between PH₃ and H⁺?
Ans: A
Phosphine (PH₃) has a lone pair of electrons on the phosphorus atom. When it reacts with H⁺ (which has an empty 1s orbital), the lone pair is donated to form a dative covalent bond (also called a coordinate bond). This results in the formation of PH₄⁺ (phosphonium ion). Since the bond is formed by sharing a lone pair, the correct answer is A.
