Superoxide is formed on heating with an excess of air by:-

1. Li, Na

2. Mg, Be

3. Na, K

4. K, Rb

A colourless salt among the following that gives violet colour to Bunsen flame is -

1. Na₂CO₃

2. K₂CO₃

3. Cu(OH)₂

4. MgCO₃

The incorrect statement among the following is-

1. Lithium is the strongest reducing agent.

2. Density of potassium is more than sodium.

3. Cs are used in devising photoelectric cells.

4. All alkali metals give a blue solution in liquid ammonia.

The suspension of slaked lime in water is known as -

1. Limewater.

2. Quicklime.

3. Milk of lime.

4. Aqueous solution of slaked lime.

Property of the alkaline earth metals that increases with their atomic number is -

1. Solubility of their hydroxides in water.

2. Solubility of their sulphates in water.

3. Ionisation energy.

4. Electronegativity.

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.

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 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