Its arbitrary. It was developed on the greek phoenetic system and never reallybwas explained.
Explanation:
Moles of NaOH = 10g / (40g/mol) = 0.25mol.
0.25mol / 500g = 0.50mol / 1000g = 0.50mol/dm³.
The molarity is 0.50mol/dm³.
Pure magnesium's formula would just be Mg because all elements except for 7 nonmetals are just left alone when they are by themselves in a formula. The 7 diatomic elements( means they have to have two of them without another element attached to it aka. a subscript two after it when it's by itself) are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. An easy way to remember the diatomic seven is that when looking at a periodic table if you trace over them from nitrogen over to fluorine and down to iodine all of those elements are diatomic + hydrogen.
And your unbalanced and balanced equations are correct.
(sorry I went on a tangent with the diatomic rules hopefully it will help you in the future though)
Identify<span> each </span>bond<span> as either </span>polar<span> or nonpolar.</span>
The radiation emitted is a beta particle with a -1 charge. <span>Beta particles have a </span><span>medium penetrating power. An emission of beta particles requires shielding because of the hazards it pose to humans. Thus, one characteristic of this radiation is that some shielding is required.</span>
