Answer:
The wavelength the student should use is 700 nm.
Explanation:
Attached below you can find the diagram I found for this question elsewhere.
Because the idea is to minimize the interference of the Co⁺²(aq) species, we should <u>choose a wavelength in which its absorbance is minimum</u>.
At 400 nm Co⁺²(aq) shows no absorbance, however neither does Cu⁺²(aq). While at 700 nm Co⁺²(aq) shows no absorbance and Cu⁺²(aq) does.
1. 5 electrons.

- Therefore, the 3d subshells blanks will be like this:
- ↑ ↑ ↑ ↑ ↑
2. 6 electrons.

- The 3d subshells blanks will be:
- ↑↓ ↑ ↑ ↑ ↑
3. 7 electrons.

- The 3d subshells blanks will be:
- ↑↓ ↑↓ ↑ ↑ ↑
Hope you could understand.
If you have any query, feel free to ask.
Answer:
3?
Explanation:
it states 3 elements names so im assuming thats it and not including the element symbols