An element has an atomic number 12. How may electrons will be present in the K, L and M energy shells of its atom ?

An element has an atomic number 12. How many electrons will be present in the K, L and M energy shells of its atom ?

The atomic number of cation M^(2+) is 12. How many electrons are present in it ?

Three elements 'X', 'Y' and 'Z' have atomic numbers 18, 19 and 20 respectively. How many electrons are present in the M shell of these elements?

Three elements 'X', 'Y' and 'Z' have atomic numbers 18, 19 and 20 respectively. How many electrons are present in the M shell of these elements?