A compound (A) is used in the preparation of washing soda to recover ammonia in Solvay's process. When CO₂ is bubbled through an aqueous solution of (A), the solution turns milky. It is used in whitewashing due to its disinfectant nature. The chemical formula of A is : 

1. $\mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2$                       

2. CaO

3. $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2$                           

4. ${\mathrm{CaCO}}_3$

The strongest factor responsible for reducing action of Li metal in an aqueous solution is :

1. Sublimation enthalpy .         

2. Ionisation enthalpy.

3. Hydration enthalpy .             

4. Electron-gain enthalpy.

The correct relation about the density of Na and K is 

1. Na > K                                                     

2. Na = K

3. K > Na                                                     

4. Li > K

The number of crystal water in Gypsum, Plaster of Paris and Epsom salt respectively are-

1. 2, 0.5, 7                                             

2. 7, 2, 1

3. 7, 0.5, 2                                             

4. 3, 4, 2

An amphoteric oxide among the following is-

1. CaO                                                     

2. SrO

3. BeO                                                     

4. MgO

The incorrect statement among the following regarding Lithium is that-

1. The hydroxide, carbonate and nitrate decompose to give the oxide on heating.

2. It is the most electronegative element of group IA.

3. The hydrogen carbonate cannot be isolated as a stable solid.

4. It forms superoxide.

The polarising power of Mg is close to that of –

1. Na                                       

2. Cs

3. Li                                         

4. K

A blue coluored solution of an alkali metal in liq NH₃ is due to the presence of -

1. ${\mathrm{M}}^{-}$atoms.                                         

2. ${\mathrm{M}}^{+}$ ions .

3. Solvated anions  .                           

4. Solvated electrons.

A compound X on heating gives a colourless gas. The residue is dissolved in water to obtain Y. Excess $C{O}_2$ is bubbled through an aqueous solution of Y, and Z is formed. Z on gentle heating gives back X. The compound X is-

1. ${\mathrm{CaCO}}_3$                                           

2. ${\mathrm{Na}}_2{\mathrm{CO}}_3$

3. ${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$                                 

4. ${\mathrm{K}}_2{\mathrm{CO}}_3$

Magnesia can be prepared by -

1. Burning Mg in air.

2. Heating hydroxide, nitrate, sulphate or carbonate of magnesium.

3. Heating Mg in steam.

4. All of the above.