Ncert Exercises & Solutions

For the electrons of an oxygen atom. The correct statement among the following is :

1.	Z_eff for an electron in a 2s orbital is the same as Z_eff for an electron in a 2p orbital.
2.	An electron in the 2s orbital has the same energy as an electron in the 2p orbital.
3.	Z_eff for an electron in 1s orbital is the same as Z_eff for an electron in a 2s orbital
4.	The two electrons present in the 2s orbital have same spin quantum numbers m_s but of opposite sign