Question

1. where do most stars fall on the hertzsprung - russel diagram?

Explanation:

The Hertzsprung - Russell (HR) diagram plots stars based on their luminosity (or absolute magnitude) and temperature (or spectral class). Most stars, including our Sun, lie on the main sequence of the HR diagram. On the main sequence, stars are in the stable phase of hydrogen fusion in their cores, converting hydrogen to helium and producing energy. This is the longest - lived phase of a star's life cycle, so the majority of stars are found here.

Answer:

Most stars fall on the main sequence of the Hertzsprung - Russell diagram.