Write the name, symbol and electronic configuration of an element $X$ whose atomic number is 11.ORCan the following groups of elements be classified as Dobereiner's triad: (a) $\mathrm{Na}, \mathrm{Si}, \mathrm{Cl}$(b) $\mathrm{Be}, \mathrm{Mg}$, $\mathrm{Ca}$Atomic mass of Be-9, Na-23, Mg-24, Si-28, Cl$35, \mathrm{Ca}-40$. Justify your answer in each case.