Tempered steel is

Match the following:

List-$I$	List-$II$
$A$. Alkali metals	$I$. $ns^2 np^6$
$B$. Alkaline earth metals	$II$. $ns^1$
$C$. Halogens	$III$. $ns^2 np^5$
$D$. Noble gases	$IV$. $ns^2$

Which of the following is not true about potash alum?

Match the following substances in List-$I$ with their uses in List-$II$:
| List-$I$ (Substance) | List-$II$ (Use) |
| :--- | :--- |
| $(A)$ $Na_2O_2$ | $(I)$ Photoelectric cells |
| $(B)$ $D_2O$ | $(II)$ Antacid |
| $(C)$ $Cs$ | $(III)$ Oxidising agent |
| $(D)$ $Mg(OH)_2$ | $(IV)$ Moderator |

Which of the following compounds is/are used for oxygenating the submarine or spaceshuttle?

Which of the following conduct electricity in the fused state?