The thermonuclear reaction of hydrogen inside the stars takes place by a cycle of operations. The particular element which acts as a catalyst is

Which of the following nuclei undergoes fission when bombarded with slow neutrons?

Light energy emitted by stars is due to

Assertion: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion.
Reason: For heavy nuclei,binding energy per nucleon increases with increasing $Z$,while for light nuclei,it decreases with increasing $Z$.

The binding energy per nucleon for deuteron $(_1H^2)$ and helium $(_2He^4)$ are $1.1 \, MeV$ and $7 \, MeV$ respectively. When two deuterons fuse to form a helium nucleus,the energy released is ........... $MeV$.

Under certain circumstances,a nucleus can decay by emitting a particle more massive than an $\alpha$-particle. Consider the following decay processes:
$_{88}^{223} Ra \rightarrow _{82}^{209} Pb + _{6}^{14} C$
$_{88}^{223} Ra \rightarrow _{86}^{219} Rn + _{2}^{4} He$
Calculate the $Q$-values for these decays and determine that both are energetically allowed.