Explanation:
Acid rain :
Acid rain is also known as acid deposition. It may be defined as a form of precipitation of the acidic components like nitric acid or sulfuric acid and fall to the earth surface from the atmosphere.
In the context, the student doing the experiment blows air in to the test tube B containing chalk dipped in water is similar to the process of acidic rain as it results in the formation of a weak carbonic acid when the carbon dioxide present in the air mixes with the chalk in the form of calcium carbonate.
Carbon dioxide reacts with water to from carbonic acid which dissociated into hydrogen ion and hydrogen carbonate ion.
