GUJARAT Class 10 - Mode of Nutrition in Plants and Animals Videos

When the leaves of a potted plant are coated with Vaseline, the stomata get blocked, which in turn blocks the exchange of gases. 

Opening and closing of stomata depend on the carbon dioxide requirement of the plant.

Baking soda decomposes to form carbon dioxide. This carbon dioxide along with the oxygen released by the plant causes the evolution of more gas bubbles during the experiment.