Question

1. when pale - yellow dinitrogen(iv) oxide is heated in a closed container, the colour changes to dark brown because a. moisture is absorbed. b. nitrogen(iv) oxide is produced. c. a precipitate is formed. d. dissociation has taken place.

Explanation:

Dinitrogen(IV) oxide ($N_2O_4$) is pale - yellow and it dissociates into nitrogen(IV) oxide ($NO_2$) when heated. $NO_2$ is dark - brown. The color change is due to the dissociation reaction $N_2O_4(g)
ightleftharpoons 2NO_2(g)$.

Answer:

B. nitrogen(IV) oxide is produced.