What is the only possible value of ml for an electron in an s orbital?

Explanation:

    is the magnetic quantum number.

The only possible value for the magnetic quantum number for an electron in an s orbital is 0.

The first three quantun numbers are:

       This quantum number is related to the type (or shape) of the orbital:

        For s orbitals

        For p orbitals

        For d orbitals

         For f orbitals

In this case, it is an s orbital, so we have .

       Since, for the s orbitals   , the only possible value for is zero.