fifth

fifteenth

second

third.

Cr

Fe

Mn

V

$$\left( {n - 2} \right){f^{1 - 14}}\,\left( {n - 1} \right){s^2}{p^6}{d^{0 - 1}}\,n{s^2}$$

$$\left( {n - 2} \right){f^{0 - 14}}\,\left( {n - 1} \right){d^{0 - 1}}\,n{s^2}$$

$$\left( {n - 2} \right){f^{0 - 14}}\,\left( {n - 1} \right){d^{10}}\,n{s^2}$$

$$\left( {n - 2} \right){d^{0 - 1}}\left( {n - 1} \right)\,{f^{1 - 14}}\,n{s^2}$$

coating it with red lead oxide

white tin plating

connecting it with Mg block

connecting it with Pb block.