Whic number of the periodic table is the atomic number and which number is the atomic mass?

The mass number (represented by the letter A) is defined as the total number of protons and neutrons in an atom. Consider the element helium. Its atomic number is 2, so it has two protons in its nucleus.

The atomic mass of a single atom is simply its total mass and is typically expressed in atomic mass units or amu. By definition, an atom of carbon with six neutrons, carbon-12, has an atomic mass of 12 amu.

r just means there's a number of carbon in teh chain. for example rcooh means that after x number of carbon, the chain ends with cooh.

explanation:

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.