Final answer:
The position of a collapsing gas cloud to a protostar and eventually a star on the Hertzsprung-Russell (H-R) diagram changes over time, moving from the right side to the left as it heats up and increases in luminosity until reaching the main sequence, which is dictated by its mass.
Step-by-step explanation:
When we look at the evolution of a collapsing gas cloud to a protostar and then to a main sequence star using a Hertzsprung-Russell (H-R) diagram, we observe that the object's position changes significantly. During the initial stages, the protostar is quite cool with a large radius, appearing on the right side of the H-R diagram, where the temperature is cooler and luminosity is lower. As the protostar collapses and its temperature increases while still not on the main sequence, it moves toward the left side of the diagram. Once the protostar becomes dense enough and hydrogen fusion begins, it moves onto the main sequence, where it will reside for most of its lifetime, steadily burning hydrogen into helium. The position of a star on the main sequence is determined by its mass, with more massive stars being more luminous and hotter, lying on the upper left of the main sequence, while less massive stars are cooler and less luminous, situated on the lower right.