Which type of radiation is the antimatter counterpart to the electron, i. e., has the same mass but opposite charge?

If the atomic mass of an atom is 34 and the atom contains 13 protons, how many neutrons does the atom contain?

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?

How do you convert 4 mmol of bromobenzene to ml?