The average number of prompt neutrons produced per fission of ${U^{235}}$ is

In a material medium,when a positron meets an electron,both particles annihilate,leading to the emission of two gamma-ray photons. This process forms the basis of an important diagnostic procedure called:

When a proton collides with a $_3Li^7$ nucleus and results in a $_4Be^8$ nucleus,the emitted particle is:

The solar energy is primarily due to:

Statement $1$: Energy is released when a heavy nucleus undergoes fission and when light nuclei undergo fusion.
Statement $2$: For heavy nuclei,the binding energy per nucleon decreases as $Z$ increases. For light nuclei,the binding energy per nucleon increases as $Z$ increases.

When two deuteron nuclei fuse to form a helium nucleus,energy is released because the mass of the helium nucleus is .....