A biologist has two brine solutions, one containing 9% salt and another containing 36% salt. How many milliliters of each solution should she mix to obtain 1 L of a solution that contains 25.2% salt?

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?