What is meant when it is said that stars have a life cycle?

stars produce living things.
stars travel in circular orbits during their lives.
stars are born, mature, and eventually die.
stars move about in their galaxies.

Amixture with the same composition throughout is!

How do dying stars contribute to the formation of planets

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)