Question

1. over time, how does the amount of hydrogen in a star change? explain your answer.

Explanation:

In a star, hydrogen is the primary fuel for nuclear fusion (specifically proton - proton chain or CNO cycle in main - sequence stars). Over time, as the star undergoes nuclear fusion reactions, hydrogen nuclei (protons) are fused together to form helium (and in more massive stars, heavier elements in later stages). So, the amount of hydrogen in a star decreases over time because it is being consumed as a reactant in the nuclear fusion processes that generate the star's energy and produce other elements.

Answer:

Over time, the amount of hydrogen in a star decreases. This is because hydrogen serves as the primary fuel for nuclear fusion within the star (e.g., in the proton - proton chain or CNO cycle for main - sequence stars). During nuclear fusion, hydrogen nuclei are fused to form helium (and heavier elements in later stages of stellar evolution), so hydrogen is consumed, leading to a reduction in its quantity within the star.