Le Chatelier's principle governs equilibrium shifts Steps:

• Identify the equilibrium: Br₂(aq) + H₂O(l) ⇌ Br⁻(aq) + HOBr(aq); orange color from Br₂(aq), products colorless.
• Adding Br⁻ (first substance): increases product concentration, shifts equilibrium left, produces more Br₂, darker orange.
• Adding OH⁻ (second substance): neutralizes implied H⁺ from full reaction (Br₂ + H₂O ⇌ HOBr + H⁺ + Br⁻), shifts right, consumes Br₂, paler orange.
• Adding H₂O (third substance): increases reactant concentration, shifts equilibrium right, consumes Br₂, paler orange.

Why B is correct:

• Matches predictions: adding Br⁻ darkens (left shift), adding OH⁻ and H₂O pale (right shifts), per Le Chatelier's principle.

Why the others are wrong:

• A: Incorrectly predicts darkening for third addition, ignoring H₂O's right shift.
• C: Wrongly predicts paler for first (Br⁻ addition darkens).
• D: Wrongly predicts paler for first and darkening for second (OH⁻ pales).

Final answer: B