For a good quality cement,the ratio of lime to the total of the oxides of $Si$,$Al$ and $Fe$ should be as close as to :

Soda lime is made from

Which of the following orders is correct?

Which pair of substances gives the same gaseous product when they react with water?

Which of the following mixtures is known as fusion mixture?

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 |