The amount of energy required to remove, an electron from the last orbit of an isolated (free) atom in gaseous state is known as ionisation energy or first ionisation of the element. Similarly the energy required for the removal of the electron from the unipositive ion (`M^(+)` produced above) is referred to as second ionization energy and thus the third, fourth etc. The ionisation energy depends on various factors like nuclear charge, size of atom, type configurations, screening effect and penetration power of the electrons.
Which of the following statements is correct?

Options

A. Ionisation energies of elements decrease along the period.
B. Ionisation energies of the II A group element are less than that of the corresponding IIIA group elements
C. Ionisation energies of group 15 elements are less than that of the corresponding group 16 elements.
D. Ionisation energy of Ga is greater than AI.

Answer

D