To show co2 is necessary for photo synthetic in short
Answers
Procedure:-
Remove food reserves from the leaves of a potted plant by keeping it in the dark for 24 hours (example; in a cupboard).
Test for starch to ensure no starch is present.
Enclose one leaf (A) in a glass flask containing some soda lime to absorb the carbon dioxide.
The leave stalk should pass through a split cork.
Support the flask with a clamp on a retort stand.
Enclose a second leaf (B) in a similar flask but without the soda lime as control experiment.
Put the plant and flask in sunlight for three (3) hours.
Remove the enclosed leaves and test for the presence of starch
Observation:-
Leaf A (in the flask with soda lime) tested negative for the presence of starch but leaf B (in the flask without soda lime) tested positive for the presence of starch.
Conclusion:-
It can therefore be concluded that, carbon dioxide is necessary for photosynthesis
Hope this helps