Question

Hydrogen can be fused to form helium at:

• A. high temperature and high pressure
• B. high temperature and low pressure
• C. low temperature and high pressure
• D. low temperature and low pressure

Answer 1

Answer: (A)

$4_1{H}^1\to {}_{2}H{e}^4+2e_{-1}^0$
The process in which lighter nuclei fuse together to form a heavier nucleus is called nuclear fusion. Nuclear fusion reaction occur at very high temperature generally $>10^{6}K$ in order to overcome electrostatic repulsion between the nuclei when they come together to fuse. The nuclear fusion reactions are therefore called thermonuclear reactions. The high temperature and pressure required for fusion to start can be made available only by nuclear fission process hence, it is also called fission fusion reaction.