Given three metals-sodium $(\mathrm{Na})$, magnesium $(\mathrm{Mg})$, copper $(\mathrm{Cu})$Activity I. When the three given metals $\mathrm{Na}$, $\mathrm{Mg}$ and $\mathrm{Cu}$ are added to magnesium chloride solution separately taken in three different test tubes, we will find that displacement reactions will take place in the following manner:This shows that $\mathrm{Na}$ is the most reactive metal as it displaces $\mathrm{Mg}$ from $\mathrm{MgCl}_2$ solution.Activity II. When $\mathrm{Na}, \mathrm{Mg}$ and $\mathrm{Cu}$ metals are taken in three different test tubes and CuSO solution is added in each test tube, we will find that displacement reactions will take place in the following manner:This shows that $\mathrm{Cu}$ is the least reactive metal. Order of decreasing reactivity: $\mathrm{Na} > \mathrm{Mg} >$ $\mathrm{Cu}$.