Astar is born whenever a nebula expands.

False.

Explanation:

The birth of a star occurs when when a nebula starts to contract (and not to expand). Due to gravitational instabilities, the nebula can fragment into smaller pieces that, in turn, can also collapse and continue to divide, eventually forming tens or hundreds of stars. As they start to contract, these fragments start a heating phase and are called protostars. When the temperature in the center of the fragments reaches a value high enough to start the nuclear fusion reaction, the contraction stops and the star is born.

false because ozone (o3) depletion does not cause global warming, but both of these environmental problems have a common cause: human activities that release pollutants into the atmosphere altering it.

global warming is caused primarily by putting too much carbon dioxide into the atmosphere when coal, oil, and natural gas are burned to generate electricity or to run our cars.

explanation: