Balance equation of calcium carbonate+water​

Atank contains 240 liters of fluid in which 10 grams of salt is dissolved. brine containing 1 gram of salt per liter is then pumped into the tank at a rate of 6 l/min; the well-mixed solution is pumped out at the same rate. find the number a(t) of grams of salt in the tank at time t.

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?

How many moles of no2 will form when 3.3 moles of cu are reacted with excess hno3?