Sodium Chloride, also known as table salt
Potassium (K), Sodium(Na), Iron(Fe), Copper(Cu), Silver(Ag), Tin(Sn), Antimony(Sb), Tungsten(W), Gold(Au), Mercury(Hg), Lead(Pb)
If you're talking about in an actual sample, you'd need more data like how many moles you have of the reactant or product.
Just in terms of the equation : there are two from the water in the reactant (left) side, and one from the sodium hydroxide and two for the hydrogen gas on the product (right) side, so 2+1+2=5 atoms of hydrogen.
