2. The hot metal objects in the photo cool quickly and soon stop glowing. What happens to the
energy as the metal parts cool?

The molecules slow down, so the energy decreases.

Explanation:

Heat makes molecules move faster, and cooling makes them go slower.

Through three stage treatment in waste water treatment plant

Explanation:

Waste water is treated through a series of stages in a waste water treatment plant to make it potable.

Basically reverse osmosis is used to make distilled water in which nutrients are added to make it drinkable.

In the first stage of treatment, all debris and suspended materials are removed through a grit. This process is known as screening

In the second stage impurities are removed through physical processes such as filtration, sedimentation, flocullation, stirring etc,

In the third stage i.e the tertiary stage biological impurities such as pathogens and bacteria are removed through advance filtration method such as reverse osmosis etc..

in this way, wastewater can be turned into drinking water.