Explain the atomic structure of calcium with suitable diagram.

An isoelectronic species are

$$\begin{gathered} \mathrm{a}\left){\mathrm{Na}}^{+} \\ \mathrm{b}\right){\mathrm{Al}}^{3+} \\ \mathrm{c}\left){\mathrm{Mg}}^{2+} \\ \mathrm{d}\right){\mathrm{Ca}}^{2+} \end{gathered}$$

Two atoms are said to be isobars if 

Match the following :
List -I :
(a) Frequency of distribution of the emitted radiation from a black body
(b) Spin quantum numbers(m_s)
(c) Angular Momentum
(d) All orbital have equal energy

List - II :
(i) degeneracy
(ii) temperature dependent
(iii) vector quantity
(iv) mass times velocity times radius 

Codes:

Nitrogen (atomic number $7$) and phosphorus (atomic number $15$) belong to group $15$  of the Periodic Table. Write the electronic configuration of these two elements. Which one of these will be more electronegative? Why? 

The schematic atomic structure of four elements is given below. Observe and choose the right statement.