Electrical conductivity of alkaline earth metals _____ from Be to Ra.

C. Increases

The electrical conductivity of alkaline earth metals increases from Be to Ra.

Here’s why:

As we move down the group (Be to Ra) in the periodic table for alkaline earth metals:

• Atomic size increases: The outer electrons are further away from the nucleus, experiencing a weaker attractive force. This makes them more readily available for conduction.
• Number of valence electrons remains the same (2): All alkaline earth metals have two valence electrons in their outermost shell, which they can contribute to conduction.

The combined effect of increasing atomic size and readily available valence electrons leads to improved electrical conductivity down the group from Be to Ra.