(N/A) $(i)$ Keep a potted plant in a dark room for $48-72$ hours to destarch its leaves. (Fig. $(a)$)
$(ii)$ Cover a portion of a leaf on both sides with strips of black paper using paper clips. This prevents sunlight from reaching the covered area. (Fig. $(b)$)
$(iii)$ Place the plant in bright sunlight for $4-6$ hours.
$(iv)$ Detach the leaf and remove the black paper strips. Perform a starch test by boiling the leaf in alcohol to remove chlorophyll and then adding iodine solution.
$(v)$ The part of the leaf that was covered with black paper does not turn blue-black,indicating the absence of starch. (Fig. $(c)$)
$(vi)$ The uncovered part of the leaf turns blue-black,indicating the presence of starch. This proves that sunlight is essential for photosynthesis.