How to figure out the [NG] of an element?

Mass → Moles and Moles → Atoms.

196.967 u . ...

So, if you are given the mass of an element, you use the periodic table to find its molar mass, and multiply the given mass by the reciprocal of the molar mass. ...

Once you have moles, multiply by Avogadro's number to calculate the number of atoms.

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

it's filtration, but this is an assumption so my apologies if i got this