Assertion : The alkaline earth metals have much higher melting and boiling points than those of the alkali metals.
Reason : The melting and boiling points of alkaline earth metal do not vary in a regular fashion.
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(B). Atom/ions of alkaline earth metals are smaller than the corresponding alkali metals. These atoms/ions are packed more closely in their lattices. Alkaline earth metals have two valence electrons and alkali metals have only one. Larger number of valence electrons leads to stronger interatomic interactions in alkaline earth metals. As a result, therefore, the melting and boiling points of alkaline earth metals are higher than those of alkali metals.