Which is correct about ionisation potential ?

Options

A. `IE_(1)` of `IE_(1)` of `O`
B. `IE_(2)` of `N gt IE_(2)` of `O`
C. `IE_(2)` of `Li gt IE_(2)` of `Ne`
D. `IE_(1)` of `Al gt IE_(1)` of `Ca`

Answer

A, C

Explanation

a. True. `IE_(1)` of `N gt IE_(1)` of `O`, due to half-filled configuration in `N`.
b. False.
`N underset(("More stable"))((2s^(2) 2p^(3))) underset(("High" IE_(1)))overset(-e^(-))rarr N^(o+) underset(("Last stable"))((2s^(2) 2p^(2)))`
`underset(("Low" IE_(2)))overset(-e^(-))rarr N^(2+)(2s^(1) 2p^(1))`
`O underset(("Last stable"))((2s^(2) 2p^(4))) underset(("Low" IE_(1))) overset(-e^(-))rarr O^(o+) underset(("More stable"))((2s^(2) 2p^(3)))`
`underset(("High" IE_(2))) overset(-e^(-))rarr O^(2+) (2s^(2) 2p^(2))`
Hence, `IE_(2)` of `O gt IE_(2)` of `N`
c. True.
`Li underset(("Less stable"))((2s^(1))) underset(("Low" IE_(1)))overset(-e^(-))rarr underset(("More stable")) (Li^(o+)(2s^(0))) underset(("High" IE_(2))) overset(-e^(-))rarr Li^(2+) (1s^(1))`
`Ne underset(("More stable")) ((2s^(2) 2p^(6))) underset(("High" IE_(1))) overset(-e^(-))rarrNe^(o+) underset(("Less stable"))((2s^(2) 2p^(5)))`
`underset(("Low" IE_(2))) overset(-e^(-))rarr Ne^(2+) (2s^(2) 2p^(4))`
`:. IE_(2)` of `Li gt IE_(2)` of `Ne`
d. False.
`IE` of `Ca gt IE` of `Al`, due to stable configuration in `Ca (4s^(2))` than in `Al (3s^(2) 3p^(1))`.