Question

Use the reaction to answer the question.

C
2
​
H
6
​
+energy→C
2
​
H
4
​
+H
2
​


Which describes this reaction, endothermic or exothermic? Why?

A. The reaction is exothermic because more energy is released than taken in.
B. The reaction is endothermic because more energy is taken in than released.
C. This reaction is exothermic because more energy is taken in than released.
D. The reaction is endothermic because more energy is released than taken in.

Answer 1

B. The reaction is endothermic because energy appears on the reactant side — more energy is taken in than released.