Question

If a star is able to stabilize after there is no more hydrogen in its core, then it is now fusing helium nuclei together in a reaction called
Select one:

a. the CNO cycle

b. the triple alpha process

c. photodissociation

d. the proton-proton chain

Answer 1

Answer: The correct answer is Option b.

Explanation:

Nuclear fusion reaction is defined as the reaction in which lighter nuclei combine together to form a single heavier nuclei.

Another name for helium nuclei is alpha particle.

For the given options:

• Option a:  The CNO cycle

This cycle is named as carbon-nitrogen-oxygen cycle. In this cycle, carbon absorbs a proton to form nitrogen which further absorbs a photon to form oxygen. Thus, helium particles are not getting fused in this process.

• Option b: The triple alpha process

This process is a set of nuclear reaction in which 3 alpha or helium nuclei combine together to form carbon nucleus.

The equation representing the fusion process follows:

$_2^4\textrm{He}+_2^4\textrm{He}\rightarrow _4^8\textrm{Be}+\gamma\\\\_4^8\textrm{Be}+_2^4\textrm{He}\rightarrow _6^{12}\textrm{C}+\gamma$

• Option c: Photo dissociation

This is defined as the process in which a chemical compound is broken down by photons. Thus, helium particles are not getting fused in this process.

• Option d: The proton-proton chain

This process is a set of nuclear fusion reactions by which stars convert hydrogen nucleus to helium nucleus. The chemical reactions for this process are:

$_1^1\textrm{H}+_1^1\textrm{H}\rightarrow _1^2\textrm{H}+_{+1}^0\textrm{e}+\text{energy}\\\\_1^2\textrm{H}+_1^1\textrm{H}\rightarrow _2^3\textrm{He}+\text{energy}\\\\_2^3\textrm{He}+_1^1\textrm{H}\rightarrow _2^4\textrm{He}+_{+1}^0\textrm{e}+\text{energy}$

Here, fusion of protons takes place.

Hence, the correct answer is Option b.