Question

Hydrogen can be fused to form helium at
A. High temperature and high pressure
B. High temperature and low pressure
C. Low temperature and high pressure
D. Low temperature and low pressure

Answer 1

Hint: A reaction is called a fusion reaction when two lower nuclei (i.e. nuclei of lower atomic number) get together and merge/fuse to form higher nuclei (i.e. nuclei of higher atomic number). In this process, there is a formation or we can say the release of subatomic particles like protons, neutrons, etc.

Complete Step by Step Answer:
As we know, the Sun is a star and it generates a very large amount of energy of its own. The reason behind that energy is that the Sun is made of layers of gas and the most important gas is hydrogen, and this hydrogen gas goes through a nuclear fusion reaction. So, we can see that at the sun due to a large number of gases the pressure at the sun is high, and also there the temperature is very high. So, we can see that for the hydrogen to be fused into helium it will require a large amount of temperature and a large amount of pressure i.e. High temperature and high pressure.

The main reason behind the requirement for this high temperature & high pressure is that to fuse two nuclei together requires a large amount of energy because there exists a high repulsion force between the two nuclei. The temperature required for this reaction is 107K & pressure required for this reaction has to be more than 2atm.
Thus, Option (A) is correct

Note: These nuclear fusion reactions are also known as thermonuclear reaction. This process also releases a large amount of energy which can result in a difference in the mass of the formed product to the total masses of the reactant.