21. In a flask, 10,3 g of aluminum reacted with 100,0 g of liquid bromine to form
aluminum bromide. After the reaction, no aluminum remained and 8.5 grams of
bromine remained unreacted. How many grams of bromine reacted? How many
grams of compound were formed?

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?