Answer: Tetrahedrally four-coordinate through chloride bridges.
- A Tetrahedrally four-coordinate through chloride bridges
- B Linearly two-coordinate via sp hybridisation as in the vapour phase
- C Octahedrally six-coordinate
- D Trigonal planar three-coordinate
Correct answer: A. Tetrahedrally four-coordinate through chloride bridges
Explanation: Solid BeCl<sub>2</sub> forms chain polymers in which each Be is bonded to four chlorines (two terminal, two bridging), giving tetrahedral four-coordination; the monomer is linear only in the vapour.
Each s-block metal ion emits a characteristic flame colour because heating excites electrons to higher energy levels; light is emitted as they fall back, with the colour determined by the specific energy gap.
Concept context
Group 1 (alkali metals) and Group 2 (alkaline earth metals). Learn their reactions with water and air, important compounds like NaOH, Na₂CO₃, and CaCO₃, and anomalous behaviour of lithium and beryllium.