Answer: Lattice enthalpy decreases faster than hydration enthalpy down the group.
- A Hydration enthalpy increases down the group
- B Lattice enthalpy decreases faster than hydration enthalpy down the group
- C The hydroxides become increasingly covalent and less ionic down the group
- D Lattice enthalpy increases down the group
Correct answer: B. Lattice enthalpy decreases faster than hydration enthalpy down the group
Explanation: Down the group the decrease in lattice enthalpy outweighs the decrease in hydration enthalpy, so the net energetics favour greater solubility of the heavier hydroxides.
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.