1. Which of the following sequences below correctly describes the evolution of the
Sun from young to old?
2. A planetary nebula is
3. Stars like the Sun probably do not form iron cores during their evolution because
4. As a star like the Sun evolves into a red giant, its core
5. A star whose mass is 5 times larger than the Sun's and whose luminosity is 100
times larger than the Sun's has a main-sequence lifetime about