The atomic numbers of $V, Cr, Mn$ and $Fe$ are $23, 24, 25$ and $26$ respectively. Which of these elements will have the highest second ionization enthalpy?

Consider the following changes:
$M_{(s)} \to M_{(g)}$ ........$(1)$
$M_{(s)} \to M^{2+}_{(g)} + 2e^-$ .......$(2)$
$M_{(g)} \to M^{+}_{(g)} + e^-$ .........$(3)$
$M^{+}_{(g)} \to M^{2+}_{(g)} + e^-$ .........$(4)$
$M_{(g)} \to M^{2+}_{(g)} + 2e^-$ ..........$(5)$
The second ionization energy of $M$ could be calculated from the energy values associated with:

The elements which occupy the peaks of the ionisation energy curve are

The first ionization energy of boron is less than that of beryllium because

Which of the following orders of ionization energy is correct?

Which of the following is a favourable factor for cation formation?