• # question_answer Hydrogen can be fused to form helium at [AFMC 2005] A) High temperature and high pressure B) High temperature and low pressure C) Low temperature and high pressure D) Low temperature and low pressure

A fusion reaction is difficult to occur because positively charged nuclei repel each-other. At very high temperatures of the order of ${{10}^{6}}$ to ${{10}^{7}}K,$ the nuclei may have sufficient energy to overcome the repulsive forces and fuse. It is for this reason, fusion reactions are also called thermonuclear reactions. Hence, hydrogen can be fused to form helium at high temperature and high pressure.