Substances that cause pollution or contaminate the environment are called .........

Global warming may result in

The pair of gases responsible for acid rain are

Determine whether the following statements are true or false:
$(1)$ The lowest region of the atmosphere where all living organisms,including humans,reside is called the troposphere.
$(2)$ The troposphere extends up to a distance of $25 \ km$ from sea level.
$(3)$ The region between $10 \ km$ and $50 \ km$ from sea level is called the stratosphere.
$(4)$ The ozone layer that protects living organisms is located in the troposphere.

The biosphere is:

Chlorine gas reacts with the aromatic ring of lignin to form which of the following substances?