This is all no chemistry but the answer is C
All the positive charge of an atom is contained in the nucleus, and originates from the protons. Neutrons are neutrally-charged. Electrons, which are negatively-charged, are located outside of the nucleus.
A gem is a crystalized mineral.
Molality is one way of expressing concentration for solutions. It has units of moles of solute per kg of solvent. From the given values, we easily calculate for the moles of solute by multiplying the mass of solvent to the molality. We do as follows:
moles solute = 0.3 (10) = 3 mol solute