1. Star A is composed of 60% hydrogen and Star B has 54% hydrogen. Which star is Older? Use scientific evidence to support your claim.

Star B is older.

Explanation:

Because the interstellar medium is 97% hydrogen and 3% helium, with trace amounts of dust, etc., a star primarily burns hydrogen during its lifetime. A medium-size star will live in the hydrogen phase, called the main sequence phase, for about 50 million years. Once hydrogen fuel is gone, the star has entered “old age.”