Write the atomic number of the element present in the third period and seventeenth group of the periodic table. 

An element A with atomic number 112 has recently been discovered. Predict its electronic configuration and suggest the group in which this element be placed.

How is the atomic radius of an element actually expressed?

The bond length of HCl bond is 136 pm. Covalent radius of hydrogen atom is 37 pm. What is the covalent radius of chlorine atom?

Which radius, vander Waal's or covalent, is larger for an atom?

What is the correlation between atomic size and ionisation enthalpy?

27.

Arrange the following in increasing order of size: Cl^-, S^2-, Ca²⁺, Ar

Arrange,  l, l^-, l⁺ in increasing order of size.

Arrange the following in decreasing order of ionic size:

Mg²⁺,  O^2-,  Na⁺, F^-,  N^3-.

Name two ions which are iso-electronic with Ar (Z = 18).