Question

The gas evolved during photosynthesis is
(a)Carbon dioxide
(b)Nitrogen
(c)Hydrogen
(d)Oxygen

Answer 1

Hint: During photosynthesis, a gas is released that is essential for all the life forms for respiration. The phytoplankton present in the ocean is responsible for 50% of this gas produced followed by land plants (25%).

Complete answer:
Plants perform photosynthesis to produce glucose and release oxygen in the atmosphere. Plants obtain the light energy from the sun, uptake water from the soil, and carbon dioxide from the air. These are utilized to produce oxygen and glucose. During the light reaction of photosynthesis, oxygen gets released. The water molecule splits during the light reaction into oxygen as well as protons and the electrons. The water gets broken into the component atoms when the electrons are stripped from the water molecules. The oxygen atoms that are released from the two water molecules combine to form diatomic oxygen. Now, as the hydrogen atoms exist as a single proton it creates a proton gradient within the space enclosed by the thylakoid membrane. The diatomic oxygen gets released and the chlorophyll center binds with a new water molecule to repeat the process. Due to these reactions, four electrons should be energized by the chlorophyll to generate one oxygen molecule.
The reaction by which oxygen gets released during the photosynthesis is represented in the equation given below.
Carbon dioxide + Water + Energy → Glucose + Oxygen
${ 6 }{ CO }_{ 2 }{ + }{ 6{ H }_{ 2 } }{ O\rightarrow }{ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }{ +{ 6{ O }_{ 2 } } }$
This is often considered a reversible reaction, as the reverse of this reaction is called respiration where the glucose and oxygen get converted into water, carbon dioxide, and energy.
So, the correct answer is, ‘Oxygen’.

Note: The maximum radiation of the sun is reflected by the earth’s atmosphere to space and the remaining energy entering the Earth is called photosynthetically active radiation (PAR). Plants utilize 2-10% of this PAR to perform photosynthesis. This smaller quantity of energy endures all life forms on this earth.