Which of the following equations does not illustrate correctly one of the reactions of chlorine?

Analyze the question: We need the equation that does NOT correctly show a reaction of chlorine. We check each option against known chlorine chemistry.

Concept: Chlorine is a strong oxidizing agent. It can displace less reactive halogens (Br⁻, I⁻) from their salts, but not more reactive ones. The reactivity of the halogens decreases down the group: F₂ > Cl₂ > Br₂ > I₂.

Checking each option:

• A. Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O This is the production of bleaching powder (calcium chlorate(I)/calcium oxychloride) from chlorine and slaked lime. It is correct and balanced.

• B. Cl₂ + 2NaF → 2NaCl + F₂ This would need chlorine to displace fluorine. Fluorine is more reactive (more electronegative) than chlorine, so chlorine cannot displace it. This reaction does not occur, so the equation is incorrect.

• C. Cl₂ + 2NaOH → NaCl + NaClO + H₂O Cold, dilute NaOH reacts with chlorine to give sodium chloride and sodium hypochlorite (bleach). It is correct and balanced.

• D. H₂S + Cl₂ → 2HCl + S Chlorine oxidizes hydrogen sulfide to sulfur and is reduced to HCl. It is correct and balanced.

Answer: Option B is the equation that does not illustrate a real reaction of chlorine.

Tip: For halogen displacement questions, remember that a halogen can only displace another halogen below it in the group. So Cl₂ can displace Br⁻ and I⁻, but never F⁻. A quick memory aid is "Fluorine is the Fiercest."