Question

Alkali and alkaline earth metals (s-block elements) generally occur in minerals and natural water in combined state as halides, sulphates, carbonates, nitrates, silicates etc. The metals are highly electropositive and their compounds are important constituents of biological fluids such as blood.

Alkali metals are typically soft, show low densities, and have low melting and boiling points. This is because they have:

• A. only one valence electron
• B. large atomic size
• C. negative values of standard reduction potentials
• D. negligible electron gain enthalpy

Answer 1

Answer: (A), (B)

The correct options are
A only one valence electron
B large atomic size

The alkali metals are soft, shiny, highly reactive and have low melting and boiling point. They have one electron in the outermost shell so they have very large atomic and ionic radii and they can lose their valence electron to form +1 oxidation state and they can easily ionize this electron.