Which expression represents the percent by mass of nitrogen in nh 4 no 3 ? a. 28 g n / 80 g nh 4 no 3 × 100% b. 14 g n / 80 g nh 4 no 3 × 100% c. 80 g nh 4 no 3 / 28 g n × 100% d. 80 g nh 4 no 3 / 14 g n × 100%

Alidded glass container is filled with a colored gas. after a period of time, it is observed that the gas is uniformly spread throughout the box and that the movement has slowed considerably. next, a warm iron plate is carefully placed under the box. why is there resumed movement of the gas in the container?