If a star is massive, it will remain in the main sequence a smaller star.

A massive star will remain in the main sequence for a shorter period of time in comparison to a smaller star

Explanation:

A larger and massive star usually remains in the main sequence up to a time when there is abundant hydrogen in its core. This hydrogen fuel helps in the process of fusion and change into helium. The luminosity and the age of a main-sequence star are directly proportional to each other and when the age of these stars increases, it gradually expands and eventually cools the outer layer of the star.

After a specific period of time, when the hydrogen fuel present in the core runs out then the process of fusion recedes, thereby stops the outward radiation of pressure. These stars typically live for a time of about 10-20 billion years and then dies off. For example, the Sun.

On the other hand, smaller and less massive stars can live up to about 80-100 billion years. For example, red dwarfs.

Thus, massive stars remain in the main sequence for a shorter period of time compared to a smaller star.

the answer for sodium is 0.186

the answer for rubidium is 0.251

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