Where do most stars fall on the diagram?

• On the diagonal main sequence band
• Scattered evenly everywhere
• Only in the giant region

What two quantities does the H-R diagram plot?

• Mass against age
• Surface temperature against luminosity
• Distance against speed

On the H-R diagram, temperature increases toward the left.

Two stars share one birthday but one has ten times the mass. Which leaves the main sequence first?

• The lighter one, because it cools faster
• Both leave at the same time
• The heavier one, because it burns fiercely

You measure a star with a hot spectrum and low luminosity. Where does it sit?

• Among the giants above the sequence
• Among the white dwarfs below the sequence
• Outside the diagram entirely

Why can a cluster H-R diagram reveal its age?

• All members share one birthday, so mass alone sets the pace
• Clusters contain only one star each
• Cluster stars never evolve

A student dates a cluster from one bright giant alone. What is wrong?

• Giants cannot appear on the diagram
• One star cannot show the turnoff pattern of the whole group
• Brightness never depends on distance

A cluster diagram shows the turnoff high on the sequence with bright giants. What does that say?

• The cluster is young, since heavy stars still linger near the sequence
• The cluster is ancient, since all stars became dwarfs
• The cluster has no massive stars at all