When a helium balloon rises in the air, it expands. If the volume of the balloon doubles, what happens to the density of the helium inside it? a. The density decreases by half
b. The density doubles
c. The density triples
d. The density stays the same

This is a mixture that has the same composition throughout.

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

A5.000 g sample of niso4 h2o decomposed to give 2.755 g of anhydrous niso4. what is the formula of the hydrate? what is the full chemical name for the hydrate? what is the molar mass of the hydrate? niso4•_h2o what is the mass % of water in the hydrate?