When a Solution of Cu(II) Chloride, CuCl₂ , Is Added

question 61

Multiple Choice

When a solution of Cu(II) chloride, CuCl₂ , is added to a solution of potassium sulfide, K₂S, a black precipitate of copper sulfide, CuS, forms. Which of the following is the molecular equation for this reaction?

• A) CuCl₂(aq) + K₂S(aq) → CuS(s) + 2 KCl(aq)
• B) Cu²⁺(aq) + Cl₂^2-(aq) + K₂²⁺(aq) + S^2-(aq) → CuS(s) + K₂²⁺(aq) + Cl₂^2-(aq)
• C) Cu²⁺(aq) + 2 Cl^-(aq) + 2 K⁺(aq) + S^2-(aq) → CuS(s) + 2 K⁺(aq) + 2 Cl^- (aq)
• D) Cu²⁺(aq) + S^2-(aq) → CuS(s)

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Definitions:

Unconditioned Stimulus (UCS)

An environmental event that can elicit an instinctive reaction without any experience.

Conditioning

A method of modifying behavior in which an individual learns to connect a previously neutral stimulus with a behavior that is sought after.

Optimum Interstimulus Interval

The ideal time gap between the presentation of a conditioned stimulus and an unconditioned stimulus for effective associative learning to occur.

Knee-Jerk Reflex

A reflexive action produced by a sharp tap on the tendons just below the kneecap, demonstrating the patellar reflex.