Match the following:

Metal	Uses
$1$. Sodium	$a$. For preparing springs
$2$. Beryllium-copper	$b$. In treatment of cancer
$3$. Radium	$c$. In preparation of aeroplanes
$4$. Magnesium-aluminium	$d$. In color industries

An extremely hot copper wire reacts with steam to give:

What is the nature of metal nitrates?

What is the mixture of $MgCl_2$ and $MgO$ called?

Write a note on $s$-block elements of the periodic table.

There are four identical containers,initially evacuated,and equal moles of the mentioned compounds are taken in each container (as shown in the diagram). The temperature is kept at $500 \ ^oC$ in each container,which are connected to a manometer. If the heights of the $Hg$ column recorded in the manometers are $x_1, x_2, x_3,$ and $x_4$ respectively,then the relation between $x_1, x_2, x_3,$ and $x_4$ is: