The standard electrode potential $\left({\mathrm{E}}^{\ominus }\right)$values of ${\mathrm{Al}}^{3+}/\mathrm{Al},{\mathrm{Ag}}^{+}/\mathrm{Ag},{\mathrm{K}}^{+}/\mathrm{K}\text{ and }{\mathrm{Cr}}^{3+}/\mathrm{Cr}$ are –1.66 V, 0.80 V, –2.93 V and –0.74 V, respectively. The correct decreasing order of reducing power of the metal is