Which of the following orders is incorrect?

Which of the following pairs shows a diagonal relationship?

Explain the following:
$(a)$ Electronegativity of elements increases on moving from left to right in the periodic table.
$(b)$ Ionisation enthalpy decreases in a group from top to bottom.

Consider the following four elements which are represented according to the long form of the periodic table. Here $W, Y$ and $Z$ are left,up and right elements with respect to the element $X$. $Y$ belongs to the $16^{th}$ group and $2^{nd}$ period. Then,according to the given information,identify the incorrect statement regarding the given elements.

Identify the incorrect order corresponding to the mentioned property.

The ionisation enthalpies of elements of the second period are given below: Ionisation enthalpy / $kcal \, mol^{-1}$: $520, 899, 801, 1086, 1402, 1314, 1681, 2080$. Match the correct enthalpy with the elements and complete the graph given in Fig. Also,write the symbols of the elements with their atomic numbers.