Zero group elements are

Na, Mg, Al is belong to 3rd period of periodic table out of there acidic oxides are formed by

The long form of periodic table is based on Bohr’s atomic model. It consists of eighteen groups and seven periods. The periods are numbered 1, 2, 3, 4, 5, 6, and 7 and each number respectively refers to the addition of last electron to the 1^st, 2^nd, 3^rd, 4^th…etc., energy levels.
Which atomic number represents an element of period 4 of the periodic table?

There was a need to arrange the elements in certain order so that their properties can be easily summarised as

Choose metalloid from the following

An element A have mass number 23 and 12 neutrons in its atoms to which group does it belong.

The energy released when an electron is gained by a neutral gaseous atom to become negatively charged ion is

An isotope of which is used in the treatment of goiter?