Question

two isotopes of hydrogen fuse to form a neutron plus the larger element, a beryllium. b carbon. c deuterium. d helium.

Explanation:

Step1: Recall nuclear - fusion reaction

The fusion of hydrogen isotopes (deuterium $^2H$ and tritium $^3H$) is a well - known nuclear reaction. The general equation for the fusion of deuterium and tritium is $^2H+^3H
ightarrow ^4He + n$, where $^4He$ is helium and $n$ is a neutron.

Step2: Analyze options

A. Beryllium is not formed in the fusion of hydrogen isotopes.
B. Carbon is not formed in this hydrogen - isotope fusion.
C. Deuterium is one of the reactants, not the product in this context.
D. Helium is the product along with a neutron when two isotopes of hydrogen fuse.

Answer:

D. Helium