Important questions based on NCERT syllabus for Chapter 10 - The s-Block Elements:
Question-1: What are the common physical and chemical features of alkali metals?
Solution: Physical properties of alkali metals:
Alkali metals have low ionization enthalpies.
Alkali metals are highly electropositive in nature.
Alkali metals exhibit +1 oxidation states in their compounds.
Alkali metals impart characteristic colours to the flame.
Question-2: Discuss the general characteristics and gradation in properties of alkaline earth metals.
Solution: Atomic size goes on increasing down the group.
Ionisation energy goes on decreasing down the group.
They are harder than alkali metals.
They are less electropositive than alkali metals.
Electropositive character increases on going down the group.
Question-3: Compare the alkali metals and alkaline earth metals with respect to (i) ionization enthalpy, (ii) basicity of oxides, (iii) solubility of hydroxides.
Solution: (i) Ionization enthalpy. Because of high nuclear charge the ionization enthalpy
of alkaline earth metals are higher than those of the corresponding alkali metals.
(ii) Basicity of oxides. Basicity of oxides of alkali metals are higher than that of alkaline earth metals.
(iii) Solubility of hydroxides of alkali metals are higher than that of alkaline earth metals. Alkali metals due to lower ionization enthalpy are more electropositive than the corresponding group 2 elements.