The electronic configurations of four elements $A, B, C, D$ are given below. Which of these elements is most likely to form an electrovalent (ionic) bond?

The main reaction during electrovalent bond formation is

Consider the Born-Haber cycle for the formation of an ionic compound given below and identify the compound $Z$ formed.
$M_{(s)}$ $\xrightarrow{\Delta H_1} M_{(g)}$ $\xrightarrow{\Delta H_2} M^{+}_{(g)}$
$\frac{1}{2} X_{2(g)}$ $\xrightarrow{\Delta H_3} X_{(g)}$ $\xrightarrow{\Delta H_4} X^{-}_{(g)}$
$M^{+}_{(g)} + X^{-}_{(g)} \xrightarrow{\Delta H_5} Z$

Given below are two statements:
Assertion $(A)$: Ionic compounds are formed by non-directional bonds.
Reasoning $(R)$: They are soluble in nonpolar solvents.
The correct answer is:

In which of the following compounds is the ratio of the size of the anion to the cation the smallest?

Write the Lewis symbols for the elements of the second period.