Answer:
Both Beryllium and Calcium have 2 valence electrons, i.e. in ther electronic configuration there are 2 electrons remaining in the outermost shell. Thus their valencies are also 2.
Electronic Configurations:
Beryllium (4) : - [2, 2]
Calcium (20) : [2, 8, 8, 2]
Hope it helps
Thank you for the question
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Edit
a. both are very reactive
b. both react readily with elements in group 1
c. both rarely combine with other elements
d. both are rare metals
(As per the suggestion of bvbfanforeverap5j54d)
