For the energy level is an atom which one of the following statement is correct ?

Options

A. There are seven principal electron energy levels
B. The second principal energy level can have four sub- energy levels and contains a maximum of eight electrons
C. The M energy level can have maximum of 32 electrons
D. The 4s sub-energy level is at a higher energy than the 3d sub-energy level

Answer

A, B

Explanation

(a) There are seven periods in the periodic table hence, 7 principal electron energy levels (n).
These electron shells are levelled as K,L,M,N,O,P and Q.
(b) The second principal shell contains four orbitals viz `2s,2p_(x),2p_(y)and2p_(z)`.