34.
(a) The number of different m
l
s is 2l + 1 = 3, and the number of different m
s
s is 2. Thus, the number
of combinations is N = (3
× 2)
2
/2 = 18.
(b) There are six states disallowed bythe exclusion principle, in which both electrons share the quantum
numbers
(n, l, m
l
, m
s
) =
2, 1, 1,
1
2
,
2, 1, 1,
−
1
2
,
2, 1, 0,
1
2
,
2, 1, 0,
−
1
2
,
2, 1,
−1,
1
2
,
2, 1,
−1, −
1
2
.