Question

Ingenhousz in an experiment showed that in bright sunlight, small bubbles were formed around the green parts of the plant, while in the dark, they did not. He identified these bubbles to be of ________________.
A. $C{O_2}$
B. ${H_2}O$
C. ${O_2}$
D. ${H_2}$

Answer 1

John Ingenhousz was a Dutch biologist, chemist and physiologist. He is best known for his discovery in photosynthesis. He showed that the light is essential to the process by which green plants absorb the carbon dioxide and oxygen was released out.

Complete answer:
A Dutch physiologist, biologist and chemist Jan Ingenhousz tried to prove in the 1770s that the plants too had a gaseous exchange. The thought of proving the plants to have a gaseous exchange came in Ingenhousz mind when he met the scientist Joseph Priestley. Ingenhousz and Benjamin Franklin stayed with a polymath and botanist Rev. John Michell in Thornhill, Yorkshire where they pursued the idea of gaseous exchange in plants based on the findings of Priestley that the plants make and absorb gases.
In 1779, Ingenhousz found that the bubbles were being exerted from the green parts of the plant in the presence of light (referred as Oxygen by Ingenhousz), whereas those bubbles stopped in the shade (light decreased). Later on, it was discovered that some of the mass of plants comes from the air, and not only the water and nutrients in the soil because it was observed that plants give carbon dioxide in dark, hence the amount of Oxygen given in the light is more than that given in the dark.

Hence, the correct answer is option (C).

Note: Ingenhousz found that:
-Light is important for the restoration (photosynthesis)
-The green part of the plant can only perform the photosynthesis.
-The damaging effect of all the living parts of the plant that damage air (respire) is neutralized by the extent of the air restoration by green plants.