Arrange $\mathrm{Na}, \mathrm{Ca}, \mathrm{K}, \mathrm{Mg}$ in the decreasing order of their reactivity.

$\mathrm{A}, \mathrm{B}, \mathrm{C}$ are three elements which undergo chemical reactions according to the following equations:

$$\begin{gathered} {\mathrm{A}}_2{\mathrm{O}}_3+2\mathrm{B}\to {\mathrm{B}}_2{\mathrm{O}}_3+2\mathrm{A} \\ 3{\mathrm{CSO}}_4+2\mathrm{B}\to {\mathrm{B}}_2({\mathrm{SO}}_4{)}_3+3\mathrm{C} \\ 3\mathrm{CO}+2\mathrm{A}\to {\mathrm{A}}_2{\mathrm{O}}_3+3\mathrm{C} \end{gathered}$$

Now answer the following questions:

(a) Which element is more reactive?

(b) Which element is the least reactive?

(c) Arrange these elements in the order of increasing reactivity.

In the redox reaction:

$\mathrm{Fe}\left(\mathrm{s}\right) + {\mathrm{Cu}}^{2+} \left(\mathrm{aq}\right)\to \mathrm{Cu}\left(\mathrm{s}\right) + {\mathrm{Fe}}^{2+}$

(a) Which one of $\mathrm{Cu}$ and $\mathrm{Fe}$ is more reactive?

(b) Which one of the two is oxidised?

(c) Which one of the two is reduced?

Complete and balance the following equation.

$\mathrm{Ca}+{\mathrm{O}}_2\to$_____

Complete and balance the following equation.

$\mathrm{Na}+{\mathrm{O}}_2\to$_____.

Complete and balance the following equation.

$\mathrm{Ca}+2{\mathrm{H}}_2\mathrm{O}\to \_\_\_\_\_$

Complete and balance the following equation.

$\mathrm{Al}+6\mathrm{HCl}\to \_\_\_\_\_$

Complete and balance the following equation.

$\mathrm{Zn}+\_\_\_\_\_\to {\mathrm{H}}_2+\_\_\_\_\_$

Complete and balance the following equation.

$\mathrm{Fe}\left(\mathrm{s}\right)+{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)\to \mathrm{\_\_\_\_}$