Yueyang SMS promotion quotation sheet

A, according to the atomic number = number of protons = number of electrons outside the nucleus, so the number of protons in a sodium atom is 1 1, so a is correct;

B. According to the information provided by the periodic table of elements, the relative atomic mass of sodium atom is 23, so B is wrong;

C, according to the relative atomic mass = proton number+neutron number: the neutron number of sodium atom is 12, so c is wrong;

D, interference term;

So choose a.