Number the steps of stellar evolution in the correct order. 1. step 1 nuclear energy runs out; death; possible supernova. 2. step 2 cloud collapses under the force of its own gravitational attraction; usually triggered by a supernova. 3. step 3 other gas and matter of the nebular cloud begin to rotate around the protostar, forming a flattened, disk. 4. step 4 nebular cloud of gas and dust. 5. step 5 stellar core heats as it grows; nuclear fusion begins and a star is born. 6. step 6 condensed material begins to combine and form a core center. as it warms, a protostar is formed.

The steps of stellar evolution:

- Nebula - an immense cloud of gas and dust in interstellar space.

- Protostar - early form of a star; lies between the collapsing of dust and beginning of nuclear fusion.

- Clouds and matters begin to rotate around the protostar. They surround protostar like a rotating disk.

- The core continues to heat and when it is hot enough, nuclear fusion begins.

- The star can go through many stages and die in different ways. One of these ways is being a supernova.

- Supernova - a gigantic explosion in which a massive star collapses and throws its outer layers into space.

Answer:

Step 1 - 4. Nebular cloud of gas and dust.

Step 2. - 2. Cloud collapses under the force of its own gravitational attraction; usually triggered by a supernova.

Step 3. - 6. Condensed material begins to combine and form a core center, as it warms, a protostar is formed.

Step 4. - 3. Other gas and matter of the nebular cloud begin to rotate around the protostar, forming a flattened disk.

Step 5. - 5. Stellar core heats as it grows; nuclear fusion begins and a star is born.

Step 6. - 1. Nuclear energy runs out; death: possible supernova.