Spin-only Magnetic Moment M³⁺

The spin-only magnetic moment value of M³⁺ ion (in gaseous state) from the pairs Cr³⁺/Cr²⁺, Mn³⁺/Mn²⁺, Fe³⁺/Fe²⁺ and Co³⁺/Co²⁺ that has negative standard electrode potential, is ____ B.M. [Nearest integer]