Which of the following ions is predicted to be a diradical by simple molecular theory?

Which of the following ions has a ground state which is predicted to be a diradical by simple molecular orbital theory?

A diradical molecule has two unpaired electrons in the same energy level (degenerate). In order to do this problem, we have to draw Frost circles.

How to draw a Frost circle?

1. Draw a circle

2. Inscribe molecule into the circle with vertex down.

3. Put a horizontal line through the middle of the circle (bonding orbitals in the bottom half of the circle and anti bonding orbitals on the top, nonbonding on the line).

4. Put a dash every time the shape touches the circle, signifying a molecular orbital

5. Distribute pi electrons from bottom up (2 electrons per orbital).

Which of the following ions has a ground state which is predicted to be a diradical by simple molecular orbital theory?