Question

plz answer the 12th one..

Answer 1

For a nuclear fusion reactor to work, the temperature and pressure would each have to be very high. These extremely high temperatures and pressures are very difficult to reproduce and are very expensive. As a result, fusion as an energy source is a long way off.
Fusion requires temperatures about 100 million Kelvin(approximately six times hotter than the sun's core).

Answer 2

The high temperature gives the hydrogen atoms enough energy to overcome the electrical repulsion between the protons.
fusion requireds 100 millon kelvin temperature.