Question

One of the following is an endothermic reaction. This is:
(a) combination of carbon and oxygen to form carbon monoxide
(b) combination of nitrogen and oxygen to form nitrogen monoxide
(c) combination of glucose and oxygen to form carbon dioxide and water
(d) combination of zinc and hydrochloric acid to form zinc chloride and hydrogen

Answer 1

(b) combination of nitrogen and oxygen to form nitrogen monoxide
When nitrogen and oxygen are heated at very high temperature (3,000^oC approx), they form nitrogen monoxide. Hence, it is an endothermic reaction.