If an atom has 15 protons, 13 neutrons, and 17 electrons, what is the atom's electrical charge?

Which material produces static charge when rubbed ?

Concerning the 10.0 ml of 0.50 m nacl to 100 ml of solution: when a solution is diluted, does it change the number of moles dissolved?

Which substances have the lowest melting points: ionic covalent, or metallic