Question

10 what is typically plotted on the vertical (top/bottom) or y axis of the hertzsprung - russell diagram?
size
temperature
absolute brightness (luminosity)
distance from earth

Explanation:

The Hertzsprung - Russell (HR) diagram is a key tool in astronomy (a subfield of Natural Science, specifically Physics - Astrophysics). In the HR diagram, the vertical (Y - axis) typically plots the absolute brightness (luminosity) of stars, while the horizontal (X - axis) often plots temperature (or spectral class). Size and distance from Earth are not the typical variables plotted on the Y - axis of the HR diagram.

Answer:

C. Absolute brightness (luminosity)