In general,the property (magnitudes only) that shows an opposite trend in comparison to other properties across a period is

In a period, the first ionisation enthalpy of the element at the extreme left and the negative electron gain enthalpy of the extreme right element, except noble gases, are respectively.

Which of the following orders is not correct for the given property?

Observe the following statements:
$I$. The physical and chemical properties of elements are periodic functions of their electronic configuration.
$II$. Electronegativity of fluorine is less than the electronegativity of chlorine.
$III$. Electropositive nature decreases from top to bottom in a group.
The correct answer is:

Among the elements $B$,$Al$,$C$,and $Si$,
$(a)$ which element has the highest first ionisation enthalpy?
$(b)$ which element has the most metallic character? Justify your answer in each case.

Which of the following is not correctly matched?