Apill that contains no active ingredients is given to a control group. which is this type of pill called?

This is usually called a placebo. They are used as control tests to make sure that a product actually works. A placebo, however, is not merely restricted to pills, though.

At the tip of each bronchiole is Alveoli.

Explanation:

In respiratory system Bronchiole are an important part. They function as a passage for the transport of air coming from the nose and mouth towards alveoli. Smooth muscles present in Bronchiole control the air flow by contraction and relaxation. At the tip of each Bronchiole air sacs called Alveoli are present. The function of alveoli is to exchange oxygen and carbon dioxide to and from blood.