Why did we study two leaves in this (Carbondioxide is necessary for photosynthesis) experiment?

Why chlorophyll is necessary for photosynthesis?

Why did we study two leaves in the half leaf experiment?

Why is chlorophyll necessary for photosynthesis?

Carbon dioxide is necessary for plants. Why do we consider it as a pollutant?

Give an experiment to prove that CO_2 is necessary for photosynthesis.

Before testing the leaf for starch at the end of the experiment, 'light is necessary for photosynthesis', the experimental leaf should be boiled in: