One among the following is the incrorrect order of increasing ionisation energy :

Options

A. `Cl^(-) lt Ar lt K^(+)`
B. `Au lt Ag lt Cu`
C. `Cs lt Rb lt K`
D. `K lt Ca lt Sc`

Answer

B

Explanation

In the Cu group, the ionization energy of Ag will be less than Cu because of bigger size of Ag . However from Ag to Au the 14f electrons are added which provide very poor shielding effect.
So due to high nuclear charge, the `I.E._1` of Au is more than Ag.
`I.E._1 = Au gt Cu gt Ag`