List of practice Questions

In comparison to boron, berylium has :

When the first electron gain enthalpy $( \Delta_{eg}H) $ of oxygen is $-141\, kJ/mol$, its second electron gain enthalpy is :

For $Na^{+}, Mg^{2+}, F^{-}$ and $O^{2-}$; the correct order of increasing ionic radii is :

In the long form of the periodic table, the valence shell electronic configuration of $5s^2 5p^4$ corresponds to the element present in :