How many molecules are in 5.4 moles of HCl?

The big bang nucleosynthesis theory states that elements were produced in the first few minutes of the big bang while elements have their origins in the interiors of stars, forming much later in the history of the universe.

Which characteristics can be used to differentiate star systems? check all that apply.

Elements in group 2 are all called alkaline earth metals. what is most similar about the alkaline earth metals?