Why is human waste hazardous when it enters the water system? for London and Ancient Rome? I will mark as brainliest

In this synthesis reaction what products will form

In pqr m< p=60 m< q= 30 and m

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?