The function of a moderator in a nuclear reactor is:

Fusion reaction is initiated with the help of

For the following two nuclear reactions,the atomic number and mass number of nuclei $X$ and $Y$ are respectively:
$(I) \, _{92}^{235}U + _{0}^{1}n \rightarrow X + _{35}^{85}Br + 3 _{0}^{1}n$
$(II) \, _{3}^{6}Li + _{1}^{2}H \rightarrow Y + _{2}^{4}He$

When a uranium isotope ${ }_{92}^{235} U$ is bombarded with a neutron,it generates ${ }_{36}^{89} Kr$,three neutrons and:

The nuclear reaction $^2H + ^2H \to ^4He$ (mass of deuteron $= 2.0141 \,amu$ and mass of $He = 4.0024 \,amu$) is

Calculate the height of the potential barrier for a head-on collision of two deuterons. (Hint: The height of the potential barrier is given by the Coulomb repulsion between the two deuterons when they just touch each other. Assume that they can be taken as hard spheres of radius $2.0 \; fm$.)