Question

Alkali and alkaline earth metals along with hydrogen and helium constitute s-block elements . They have low ionization enthalpies and hence exhibit characteristic flame colouration . They have highly negative electrode potentials and hence are strong reducing agents . Their solutions in liquid ammonia are conducting and also act as strong reducing agents than hydrogen , they are usually prepared by electrolysis of their fused chlorides . Their oxides are basic and the basic strength increases down the group . The solubility of carbonates and sulphates of alkali and alkaline earth metals show opposite trends . The carbonates of alkaline earth metals and lithium carbonate decompose on heating while the carbonates of other alkali metals do not decompose on heating . The bicarbonates of both alkali and alkaline earth metals on heating give carbonates .
The basic character of the oxides , MgO , SrO , `K_(2)O , NiO` and `Cs_(2)O` increases in the order :
A. `MgO gt Sr O gt K_(2)O gt NiO gt Cs_(2)`
B. `Cs_(2) lt K_(2)O lt MgO lt SrO lt NiO`
C. `NiO lt MgO lt SrO lt K_(2)O lt Cs_(2)O`
D. `K_(2)O ltNiO lt MgO lt SrO lt Cs_(2)`

Answer 1

Correct Answer - C
Alkali metal oxides are most basic followed by alkaline earth metal oxides while transition metal oxides are least basic . Amongst alkali and alkaline earth metal oxides , basicity increases down the group . Thus , `Cs_(2)O` is more basic than `K_(2)O` and `SrO` is more basic than MgO . therefore , the overall order is `: NiO lt MgO lt SrO lt K_(2)O lt Cs_(2)O`.