The Azimuthal quantum number for the valence electrons of Ga$$^+$$ ion is (Atomic number of Ga = 31)

Gallium (Ga) has atomic number 31. Its ground state electronic configuration is [Ar] 3d¹⁰ 4s² 4p¹.

Ga⁺ ion is formed by removal of one electron from the neutral Ga atom. The electron is removed from the outermost subshell, which is 4p¹. So the configuration of Ga⁺ is [Ar] 3d¹⁰ 4s².

The valence electrons of Ga⁺ are those in the outermost (valence) shell, which is the 4th shell. The electrons present in the 4th shell are the 4s² electrons. The 3d electrons, though filled after 3p, are considered inner (core) electrons once the 4s is filled, but for Ga⁺ the outermost subshell with electrons is 4s.

For the 4s electrons, the azimuthal (angular momentum) quantum number $$\ell = 0$$.

Therefore, the azimuthal quantum number for the valence electrons of Ga⁺ is $$\ell = 0$$.