For the electrons of oxygen atom, which of the following statemetns correct?

Options

A. `Z_(eff)` for an electron in a 2s orbital is the same as `Z_(eff)` for an electron in a 2p orbtial
B. An electron in the 2s orbtial has the same energy as an electron in the 2p orbital
C. `z_(eff)` for an electron in 1s orbital is the same as `z_(eff)` for an electron in a 2s orbital
D. The two electrons present in the 2s orbtial have spin quantum numbers `m_(s)` but of opposite sign.

Explanation

(a) Electrons in 2s and 2p orbtials have different screen effect. Hence their `Z_(eff)` is different.
`Z_(eff)` of 2s orbital `gtZ_(eff)` of 2p orbital
(b) Energy of 2s orbital `lt` energy of 2p orbtial
Hence, it is not correct.
(c) `Z_(eff)` of 1sorbital`cancel=Z_(eff)` 2s orbital
Hence, it is incorrect.
(d) For the two electrons of 2s orbtial, the value of `m_(s)` is `+(1)/(2)` and `-(1)/(2)`
hence, it is correct.