The set representing the correct order of the first ionisation potential is

Options

A. `KgtNagtLi`
B. `BegtMggtCa`
C. `BgtCgtN`
D. `GegtSigtC`

Answer

2

Explanation

Down the group the effective nuclear charge remains almost constant. But down the group with increasing atomic number the number of atomic orbits increases and there by atomic size increases. As a result, the distance of valence shell electron from nucleus increases and attraction between them decreases and therefore ionization energy decreases.