Analysis show that nickel oxide consists of nickel ion with `96%` ions having `d^(8)` configuration and `4%` having `d^(7)` configuration. Which amongst the following best represents the formula of the oxide?

Options

A. `Ni_(1.02)O_(1.00)`
B. `Ni_(0.96)O_(1.00)`
C. `Ni_(0.98)O_(0.98)`
D. `Ni_(0.98)O_(1.00)`

Answer

D

Explanation

`Ni = 3d^(8) 4s^(2)` (At. No. `= 28`),
`:. Ni^(2+) = 3d^(8)` and `Ni^(3+) = 3d^(7)`
Hence, `96%` ion of `Ni^(2+)` and `4%` ions of `Ni^(3+)` are present.
Let number of `O^(2-)` ion present in the crystal `= x`.
Applying electroneutrality rule,
Total positive charge `=` Total negative charge
`= 96 xx 2 (+ve "charge") + 4 xx 3 (+ve "charge")`
`= x + 2 (-ve "charge")`
`:. 96 xx 2 + 4 xx 3 - 2 x = 0`
`:. x = 1.02`
So formula of crystal `Ni_(1.00)O_(1.02)` or `Ni_(0.98)O_(1.00)`.