Write the atomic number and electronic configuration of the following elements.
(i) Sodium
(ii) Chlorine
(iii) Neon
(iv) Magnesium
Choose the incorrect statement/statements from the following:
(i) Atomic mass of hydrogen is 1 u. (ii) Atomic mass of helium is 2 u. (iii) Atomic mass of chlorine is 17 u. (iv) Atomic mass of phosphorous is 31 u.