(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.