Alkali metals are characterised by:

1. Good conductors of heat and electricity.

2. High melting points.

3. Low oxidation potentials.

4. High ionisation potentials.

An ion that has the largest size among the following is :

1. Li⁺(aq)

2. Cs⁺(aq)

3. Li⁺(g) 

4. K⁺(aq)

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 property of alkali metals that increases with increasing atomic number is -

1. First ionization energy.                         

2. Electronegativity.

3. Hydration energy of the univalent ion.   

4. Atomic radius.

The cation of alkali metals are found as M(H₂O)⁺_n in H₂O.

The value of 'n' is maximum for -

1. Na⁺

2. K⁺

3. Rb⁺

4. Li⁺

The incorrect statement among the following is -

1. Li⁺ has minimum degree of hydration among alkali metal cations.

2. The oxidation state of K in KO₂ is +1

3. Sodium is used to make Na / Pb alloy.

4. MgSO₄ is readily soluble in water.

Lithium shows a diagonal relationship with : 

1. Sodium

2. Magnesium

3. Calcium

4. Aluminium

Alkali metals, though white, impart characteristic color to the flame because of

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

1. Li, Na

2. Mg, Be

3. Na, K

4. K, Rb

In the reaction $\mathrm{M}+{\mathrm{O}}_2\to {\mathrm{MO}}_2$ (superoxide) the metal is -

1. Li                 

2. Na

3. K                 

4. Ba