Question

Solar energy is mainly caused due to

• A. burning of hydrogen in the oxygen
• B. fission of uranium present in the Sun
• C. fusion of protons during synthesis of heavier elements
• D. gravitational contraction

Answer 1

The Correct Option is C

To understand why "fusion of protons during synthesis of heavier elements" is the correct answer, let's explore the fundamental processes responsible for solar energy: 

1. Fusion of Protons: The Sun's energy is primarily produced by nuclear fusion, a process occurring in its core. Here, hydrogen nuclei (protons) fuse to form helium through a series of reactions known as the proton-proton chain. In this series of reactions, four hydrogen nuclei combine to form one helium nucleus, with a release of energy. This energy is the primary source of the Sun's luminosity and hence, solar energy.
2. This process can be represented as: \(4 \text{H} \rightarrow \text{He} + 2\beta^+ + 2\nu + \text{Energy}\), where \(\beta^+\) is a positron and \(\nu\) is a neutrino.
3. Incorrect Options Explained:
   • Burning of hydrogen in oxygen: This option describes a chemical reaction, not a nuclear one. The Sun's environment doesn’t have enough free oxygen for hydrogen to burn in this manner.
   • Fission of uranium present in the Sun: Nuclear fission involves splitting heavy elements like uranium, not fusing lighter elements, and it is not the primary reaction occurring in the Sun's core.
   • Gravitational contraction: While it was a concept in the early formation stages of the Sun, it is not responsible for ongoing solar energy production.

Thus, the Sun's energy largely stems from the fusion of protons, leading to the synthesis of heavier elements like helium, making option "fusion of protons during synthesis of heavier elements" correct.