\ extbf{Solution:} \ extbf{i)} \\bullet The aim of the experiment is to show that plants require CO_2 for photosynthesis. \\bullet CO_2 and water are raw materials that are used by the plant to convert it into carbohydrates by using sunlight and in the presence of chlorophyll. \ extbf{ii)} \\bullet The leaf inside the flask does not get atmospheric CO_2 because KOH absorbs all the CO_2 in the flask. \\bullet Since KOH absorbs CO_2 , therefore, if the leaf does not produce any starch, this will prove that leaves require carbon dioxide to perform photosynthesis (make food on their own). \ extbf{iii)} \\bullet KOH is used to absorb all the CO_2 present in the flask. \\bullet An alternative chemical that can be used instead of KOH is NaOH. \ extbf{iv)} \\bullet KOH absorbs all the CO_2 present in the flask and therefore, leaf 1 does not get CO_2 . \\bullet The absence of CO_2 inside the flask does not allow leaf 1 to produce starch and the leaf does not turn blue-black when a starch test is done (iodine is added and the yellow colour of iodine remains the same) \\bullet Leaf 2, on the other hand, gets atmospheric CO_2 and at the end of the starch test, the yellow colour of iodine turns into a blue-black colour due to the presence of starch in the leaves