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.

Based on the equation and the information in the table, what is the enthalpy of the reaction?

If the density of water is 1.0 g/cm3, which of these materials would float in water, based on their densities? check all that apply. aluminum cork iron lead wax

The characteristic of two different types of reactions are shown below. reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of and element. which statement is true about the atoms of the elements that participate in the two reactions? a: their identity changes in both reaction a and b. b: their identity changes in reaction a but not b. c: their identity changes in reaction b but not a. d: their identity remains the same.