4. stellar equilibrium is the balance of reactions and forces that allows a star to maintain its size and shape.

a. what reactions occur within a star in stellar equilibrium?
b. what effect do these reactions have on the star?
c. what forces hold a star together in stellar equilibrium?

A. Nuclear fussion reactions.

B. Generates an internal pressure that try to expand the star.

C. Gravity force and internal pressure.

Explanation:

In a star there is a balance between gravity force, that attracts the stellar gas towards the center and compressing it, and the pressure due to nuclear fusion reactions that occur within the star, that acts in the opposite direction to gravity trying to expand the star. Therefore, the star is in equilibrium and adopts a stable spherical shape.

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