Which of the following order is wrong-

Options

A. `NH_(3) lt PH_(3) lt AsH_(3) `- Acidic
B. `Li lt Be lt B C-` 1st Ionisation potential
C. `Al_(2) O_(3) lt MgO lt Na_(2)O lt K_(2) O-` Basic
D. `Li^(+) lt Na^(+) lt K^(+) lt Cs^(+) -` Ionic radius

Answer

B

Explanation

Li,Be,B and C are present in II nd peroid. In a period form left to right ionisation potential increase.
`underset("Li Be B C")overset("Ionisation potenional increases")to`
But in cases of Be and B, Be has higher ionisation potential than B due to stable configuration of Be.
`""_(4)Be = 1s^(2),2s^(2)`
Stable configuration (due to fully-filled orbital)
`""_(5)B = 1s^(2),2s^(2)2p^(1)`
Unstable configuration
So, the corrcet order of ionsation potential of given elements is
`Li lt B lt Belt C`