Answer: Na dissolves in mercury forming a liquid alloy (amalgam) that is safer and less reactive than pure Na.
- A Na dissolves in mercury forming a liquid alloy (amalgam) that is safer and less reactive than pure Na
- B Sodium chemically reacts with mercury to form a distinct crystalline ionic compound in routine practice
- C Mercury metal directly oxidises the sodium as the two substances come into contact overall in most cases
- D Sodium and mercury are actually largely immiscible and rarely form an alloy under typical conditions
Correct answer: A. Na dissolves in mercury forming a liquid alloy (amalgam) that is safer and less reactive than pure Na
Explanation: Amalgams are alloys of mercury; Na dissolves in Hg, diluting its reactivity while retaining reducing power, making it safer to handle.
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.