Which of the following is a possible set of n, l, ml, and ms quantum numbers for the last electron added to form an As3+ ion?

Question

(a)

3, 1, -1, ½

(b)

4, 0, 0, -½

(c)

3, 2, 0, ½

(d)

4, 1, -1, ½

(e)

5, 0, 0, ½

Answer 1

As is [Ar]3d10 4s2 4p3. To make the +3 ion we remove the last three electrons so the last electron added is the 4s.
n = 4
all s electrons are l = 0
the spin of an s electron is either +1/2 or -1/2. You should be able to pick out the answer from this.

Answer 2

If the energy state of the H-atom is changed from n=3 to n=2:

What is the energy change in joules?

Energy Change = J

What is the frequency of the photon emitted?
Frequency = Hz