hellooo I don't think im writing in the correct thing uh you don't have to do all of them just like one or two so I can get an idea of what I'm supposed to do, please :)

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.

The molality of calcium chloride (cacl2) in an aqueous solution is 2.46 m. what is mole fraction of the solute?

Which theory was contradicted by experiments with the photoelectric effect? light spreads out after it passes through a small opening. as soon as light strikes metal, electrons will be ejected. visible light, regardless of color, will cause the ejection of electrons when striking metal. the kinetic energy of ejected electrons depends on the frequency of light that strikes the metal.