Question

Which of the following reactions is given by Van Niel?
1. $2{{H}_{2}}O+C{{O}_{2}}\to 2A+C{{H}_{2}}O+{{H}_{2}}O$
2. $C{{O}_{2}}+{{H}_{2}}O\to C{{H}_{2}}O+{{O}_{2}}$
3. $6C{{O}_{2}}+12{{H}_{2}}O\to {{C}_{6}}{{H}_{12}}{{O}_{6}}+6{{H}_{2}}O+6C{{O}_{2}}$
4. $2{{H}_{2}}O+C{{O}_{2}}\to C{{H}_{2}}O+{{H}_{2}}O$

Answer 1

Photosynthesis is a light-dependent redox reaction in which hydrogen from an oxidizable compound reduces carbon dioxide to cellular materials.

Complete step-by-step answer:
A microbiologist, Cornelius van Niel discovered that hydrogen released from an oxidizable compound reduces carbon dioxide to carbohydrates. The oxygen evolved by the green plants come from water not from carbon dioxide. This observation was done on purple and green bacteria. Photosynthesis takes place in the green leaves of plants and other green parts of the plants (stem).
The most active site for photosynthesis in the higher plants is the mesophyll of leaves and the mesophyll cell have numerous chloroplasts which are rich in specialised light absorbing green pigment called chlorophyll. This is the experiment which increases our understanding towards Photosynthesis.
This hypothesis was later proved by using radioisotopic techniques.
$2{{H}_{2}}A+C{{O}_{2}}\to 2A+C{{H}_{2}}O+{{H}_{2}}O$
Where ${{H}_{2}}A$ is the oxidizable compound (${{H}_{2}}O$ and ${{H}_{2}}S$).
The correct equation for the process of photosynthesis is:
$6C{{O}_{2}}+12{{H}_{2}}O\to {{C}_{6}}{{H}_{12}}{{O}_{6}}+6{{H}_{2}}O+6C{{O}_{2}}$
Where ${{C}_{6}}{{H}_{12}}{{O}_{6}}$ is glucose and ${{O}_{2}}$ is released from water.

So, the correct answer is option A.

Note: Ruben, Kamen et. Al. Used heavy, non-radioactive, stable isotope of oxygen to prove that oxygen is evolved during light reaction that comes from water not from carbon dioxide.
Part of the spectrum used in photosynthesis has a wavelength of 400-700 nm and it is called photosynthetically active radiation.