1. Quiz_26 Multi-electron atoms & Exclusion Principle
Physics 274
11/4/2016

2. B. An n=3 to n=2 hydrogen transition
Q.2
The 21cm hydrogen line (energy 5.87 μeV) is the result of the following transition:
A. Spin-Orbit (electron spin – orbital angular momentum) coupling with l changing by one unit.
B. An n=3 to n=2 hydrogen transition
C. A “spin-flip” transition (due to electron spin-nuclear spin interaction)
D. An ml=1 to ml=0 hydrogen transition C

3. In helium, which of the following statements is true ?
Q.1
In helium, which of the following statements is true ?
A. There is one electron in the 1s state and one in the 2s state. The valence electron in the 2s state allows helium to be reactive.
B. There are two electrons in the 1s state with opposite szvalues to satisfy the Pauli exclusion principle. Since there are no extra valence electrons, helium is a “noble” gas.
C. Helium has two electrons in the 2s state with oppositely oriented spins. Hence, helium is non-reactive.
D. Helium and Lithium have identical QM electronic structures. B

4. Q.3
2,1,0 B

5. Q.4
First fill up the 1S, then 2S and then 2p levels2,2,5 A