A Levels Chemistry (9701)•9701/12/O/N/20
Explanation
Flame Test and Basicity of Barium Compounds Steps:
- Identify flame color for barium metal: burns with green flame due to Ba²⁺ ions.
- Determine pH of barium hydroxide solution: strong base, saturated solution has pH ≈13.
- Compare to options: seek match for green flame and pH 13.
- Select option with both correct properties for barium.
Why B is correct:
- Matches barium's green flame test and high pH (13) from strong base dissociation: Ba(OH)₂ → Ba²⁺ + 2OH⁻.
Why the others are wrong:
- A: Incorrect pairing; does not align with barium's properties (possibly mismatched pH or color).
- C: Lacks specified values; insufficient data to confirm.
- D: White flame incorrect for barium (e.g., typical for calcium or magnesium).
Final answer: B
Topic: Group 2
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