Assertion : As the electropositive character increases down the group, the stability of carbonates and hydrogen carbonates of alkali metals increases.

Reason : Lithium carbonates is not so stable to heat ; lithium being very small in size polarizes a large $C{O}_3^{2-}$ion leading to the formation of more stable $L{i}_{2}O$ and $C{O}_2$.

1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

The following is the correct order of chemical reactivity with water according to electrochemical series-

1. K>Mg>Cu>Zn                                     

2. K>Mg>Zn>Cu

3. Cu>Zn>K>Mg                                     

4. Mg>K>Cu>Zn

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

1. Li                 

2. Na

3. K                 

4. Ba 

The reaction of sodium with water is highly exothermic. The rate of reaction can be lowered by-

(1) Decreasing the temperature 

(2) Mixing with alcohol

(3) Mixing with acetic acid 

(4) Making an amalgam

Sodium reacts with water less vigorously than potassium because-

1. It has a higher atomic weight.

2. It is less electropositive .

3. It is more electronegative. 

4. It is a metal .

The correct relation about the density of Na and K is 

1. Na > K                                                     

2. Na = K

3. K > Na                                                     

4. Li > K

Which of the following does not give an oxide on heating-

(1) $MgC{O}_3$                                                   

(2) $L{i}_{2}C{O}_3$

(3) $ZnC{O}_3$                                                   

(4) $K_{2}C{O}_3$ 

The reason for a lower basicity of hydroxides of alkaline earth metals than alkali metals is : 

1. Alkali metals form ionic compounds.

2. The bond strength of oxygen is more for alkali metals.

3. The electropositivity of alkali metals is more than alkaline earth metals.

4. The electropositivity of alkali metals is less than alkaline earth metals.

In $K^{+}{F}^{-}$ ionic radius of $F^{-}$ is more while atomic radius of $K^{+}$ is –

(1) Less than $F^{-}$

(2) More than $F^{-}$

(3) Equal to $F^{-}$

(4) None of these

Lattice energy is lowest for –

1. LiF                                                       

2. NaCl

3. KBr                                                       

4. CsI