Question

place the following events of star formation in order.
a new star is formed
the protostars temperature increases
a protostar forms as the nebula contracts
the fusion of hydrogen into helium begins
a nebula collapses in on itself due to its own gravity

Explanation:

Star formation begins with a nebula collapsing due to gravity. This forms a protostar. As the protostar contracts, its temperature rises. When hot enough, hydrogen fusion starts. This stable fusion marks a new star.

Answer:

1. A nebula collapses in on itself due to its own gravity
2. A protostar forms as the nebula contracts
3. The protostar's temperature increases
4. The fusion of hydrogen into helium begins
5. A new star is formed