Question

In Mendeleev's periodic table the elements were arranged in the increasing order of their atomic masses. However cobalt with atomic mass 58.93 u was placed before nickel having an atomic mass
of 58.71 u. Give reason for the same.
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Answer 1

Answer:

cobalt placed before the nickel in the periodic table.

Explanation:

Because nickel has fewer electrons. Cobalt has low density.