What is the mass of 0.015 moles of Na2SO4?

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

A5.00 g of a in . g of at aa 5.00 g of b in . g of .?at .

Which example is a mechanical wave?     a.microwave    b.radio wave    c.water wave    d.ultraviolet light