In which group of elements of the modern periodic table are halogen placed?

The electronic configuration of an element is given as $1{\mathrm{s}}^2$. In which group and period of the periodic table is it placed?

The electronic configuration of element are - $1{\mathrm{s}}^2,2{\mathrm{s}}^2,2{\mathrm{p}}^6$, In which group and period of the periodic table they are placed?

For the pairs, indicate which of the two species is of large size: ${\mathrm{Fe}}^{+2}$ or ${\mathrm{Fe}}^{+3}$.

For the pair, indicate which of the two species is of large size: ${\mathrm{Mg}}^{2+}$ or ${\mathrm{Ca}}^{2+}$.

Select the smaller ion from the pairs: ${\mathrm{K}}^{+}, {\mathrm{Li}}^{+}$.