Question

define fusion Kelvin and atmospheric pressure

Answer 1

The process of melting ,that is , change of solid state is known as fusion kelvin.
The heat energy required to change 1 kg of a liquid to gas is known atmosphere pressure

Answer 2

$\huge\pink\star$★Fusion requires temperatures about 100 million Kelvin (approximately six times hotter than the sun's core). At these temperatures, hydrogen is a plasma, not a gas. Plasma is a high-energy state of matter in which all the electrons are stripped from atoms and move freely about.