Which element has quantum numbers 3 1 0 - 1/2

The element is Aluminium. (assuming that the given quantum number set is for the valence electron of the unknown element)

Explanation:

The given quantum numbers are:

n=3 (Principal Quantum Number)

l=1 (Azimuthal Quantum Number)

m=0 (Magnetic Quantum Number)

s = - 1/2 (Spin Quantum Number)

The given set of quantum numbers refer to the 3p orbital.

Assuming that this the valence electron of the element, the unkown element is Aluminium.