Classification ...

Two elements $$X$$ and $$Y$$ contain only one electron in the outer level. Element $$X$$ is reactive and loses electron easily while element $$Y$$ is relatively unreactive and non-corrosive. The elements $$X$$ and $$Y$$ respectively are:

Who is father of the Periodic Table of Elements?

$$A,\ B,\ C$$ are three elements with the atomic number $$Z-1, Z, Z+1$$ respectively. $$B$$ is an inert gas. Predict the group of $$A$$ and $$C$$.

The correct oreder of electron affinity is :

Element with similar chemical properties:

The amount of energy relased when $$10^o$$ atoms of iodine in vapour state are converted to $$I^-$$ ions is $$4.9\times 10^{-13}J$$. What is the electron affinity of iodine in eV per atom?

Which one of the following arrangement represents the correct order of electron gain enthalpy (with negative sign) of given atomic species?

Ionization enthalpy of $$F  = 320 kJ mol^{-1}$$. The electron gain enthalpy of flourine would be:

Match the column:- 

The number of electrons having $$n + s = 2.5$$ in sulphide ion is: