Question

1. match the correct term to complete the sentence.

a(n) ___________ reaction absorbs heat from the surroundings during a chemical reaction.
choices

• exothermic
• endergonic
• exergonic
• endothermic

1. choose the best answer.

which type of reaction is this?
cdso₄ (aq) + k₂s (aq) → k₂so₄ (aq)+cds (s)

• redox
• acid - base
• precipitation

Explanation:

Question 17

To solve this, we recall the definitions of each term:

• Exothermic: Releases heat.
• Endergonic: Requires energy (not specifically heat absorption in the same context).
• Exergonic: Releases energy.
• Endothermic: Absorbs heat from surroundings.

The sentence describes a reaction that absorbs heat, so the correct term is endothermic.

• Redox reaction: Involves electron transfer (change in oxidation states). Here, oxidation states of Cd, S, K, O don't change.
• Acid - base reaction: Involves proton (H⁺) transfer, which is not seen here.
• Precipitation reaction: A reaction where an insoluble solid (precipitate) is formed from aqueous solutions. In the reaction $\ce{CdSO_{4}(aq) + K_{2}S(aq) -> K_{2}SO_{4}(aq) + CdS(s)}$, $\ce{CdS}$ is a solid (precipitate) formed from two aqueous solutions.

Answer:

endothermic

Question 18