$$\stackrel{\mathrm{NaNO}_{2}}{\longrightarrow} / \stackrel{\mathrm{HCl}}{\longrightarrow} / \stackrel{\mathrm{KBr}}{\longrightarrow} / \stackrel{\mathrm{H}^{+}}{\longrightarrow}$$

$$\stackrel{\mathrm{Sn} / \mathrm{HCl}}{\longrightarrow} / \stackrel{\mathrm{KBr}}{\longrightarrow} / \stackrel{\mathrm{Br}_{2}}{\longrightarrow} / \stackrel{\mathrm{H}^{+}}{\longrightarrow}$$

$$\stackrel{\mathrm{B} \mathrm{B}_{2} / \mathrm{Fe}}{\longrightarrow} / \stackrel{\mathrm{Sn} / \mathrm{HCl}}{\longrightarrow} / \stackrel{\mathrm{NaNO}_{2} / \mathrm{HCl}}{\longrightarrow} / \stackrel{\mathrm{CuBr} / \mathrm{HBr}}{\longrightarrow}$$

$$\stackrel{\mathrm{Sn} / \mathrm{HCl}}{\longrightarrow} / \stackrel{\mathrm{Br}_{2}}{\longrightarrow} / \stackrel{\mathrm{NaNO}_{2}}{\longrightarrow} / \stackrel{\mathrm{NaBr}}{\longrightarrow}$$

5.92, 4.90 and 0 BM

4.90, 0 and 1.73 BM

5.82, 0 and 0 BM

4.90, 0 and 2.83 BM

Red P + Cl₂

$$N{H_2} - N{H_2}/{C_2}{H_5}\mathop O\limits^\Theta \mathop N\limits^ \oplus a$$

NaBH₄

Ni/H₂

Cr < Zn < Co < Cu < Fe

Cr < Fe < Co < Cu < Zn

Zn < Cr < Fe < Co < Cu

Zn < Cu < Co < Fe < Cr