The compound (X) on heating gives a colorless gas and a residue that is dissolved
in water to obtain (B). Excess of CO${}_2$ is bubbled through an aqueous solution of B, C is
formed. Solid (C) on heating gives back X. (B) is

1. CaCO${}_3$

2. Ca(OH)${}_2$

3. Na${}_2$CO${}_3$

4. NaHCO${}_3$

Among the following the least thermally stable carbonate is : 

$1.$ ${\mathrm{K}}_2{\mathrm{CO}}_3$

2. ${\mathrm{Na}}_2{\mathrm{CO}}_3$

3. ${\mathrm{BaCO}}_3$

4. ${\mathrm{Li}}_2{\mathrm{CO}}_3$

One mole of calcium phosphide upon reacting with water gives:

1. One mole of the phosphene.

2. Two moles of phosphoric acid.

3. Two moles of phosphine.

4. One mole of phosphorus pentaoxide.

Which of these is not used as fuel in the rocket propellants?

1. Liquid He

2. Liquid hydrogen

3. Kerosene

4. Liquid hydrazine

Fire extinguishers contain $H_{2}S{O}_4$ and __ _

1. ${\mathrm{NaHCO}}_3$ and ${\mathrm{Na}}_2{\mathrm{Co}}_3$

2. ${\mathrm{NaHCO}}_3$ solution

3. ${\mathrm{Na}}_2{\mathrm{Co}}_3$

4. ${\mathrm{CaCO}}_3$

Sodium nitrate decomposes above 800°C and does not give:

1. ${\mathrm{N}}_2$

2. ${\mathrm{O}}_2$

3. ${\mathrm{NO}}_2$

4. Na₂O

On heating sodium metal in a current of dry ammonia gas the compound formed is:

(1) sodium nitrate

(2) sodium hydride

(3) sodium amide

(4) sodium azide

The electrolyte employed in the extraction of sodium by Down's electrolysis method is:

(1) An aqueous solution of NaCl

(2) Molten NaCl

(3) Molten NaOH

(4) A molten mixture of ${\mathrm{MgCl}}_2$, and NaCl

Which statement is false for alkali metals?

(1) Lithium is the strongest reducing agent

(2) Sodium is amphoteric in nature

(3) Li⁺ is exceptionally small

(4) All alkali metals give blue solution in liquid ammonia

An aqueous solution of a salt of sodium (NaX) on boiling with ${\mathrm{MgCl}}_2$ gives white precipitate, hence anion X is:

1. ${\mathrm{HCO}}_3^{-}$

2. ${\mathrm{NO}}_3^{-}$

3. ${\mathrm{CO}}_3^{2-}$

4. ${\mathrm{SO}}_3^{2-}$