Question

Which event signals the birth of a star? A core shrinks and explodes in a supernova. A protostar collapses, becoming dense and hot. Extreme heat and pressure causes nuclear fusion. A mass of gas and dust grows and forms a protostar.

Answer 1

Answer: Extreme heat and pressure causes nuclear fusion.

Explanation:

A star is formed by the fusion of the atoms of hydrogen to helium. This process releases a lot of energy in the heat. This process involves the fusion of four atoms of hydrogen with one atom of helium. The external heat, pressure and gravitational force are responsible for the nuclear fusion reactions. The heat produce creates a pressure to allow the fusion of the helium atom to carbon. These fusions are necessary to provide a shape to the star.

Answer 2

Extreme heat and pressure causes nuclear fusion.