Answer: The number of atoms after fusion reaction decreases.
Step-by-step explanation:
There are two types of nuclear reactions:
- Nuclear fission reactions: In this type of reaction, the heavier atoms splits into two or more lighter atoms. The number of atoms formed in this reaction increases from the given atoms.
- Nuclear fusion reactions: In this type of reaction, two or more lighter atoms combine to form a heavier atom. The number of atoms formed in this reaction decreases from the given atoms.
We are given:
Number of atoms at the start of nuclear fusion reaction = 12 atoms.
So, when these atoms undergo fusion reaction, the number of atoms formed at the end of the reaction will decrease.
Hence, the number of atoms after fusion reaction decreases.