Question

Which of the following pair of elements was not placed according to Mendeleev's Periodic Law by Mendeleev in his periodic table?
(a) Co and Ni
(b) Li and Be
(c) N and O
(d) Fe and Co​

Answer 1

Answer:

a) Co and Ni

Explanation:

Cobalt(Co) is placed before Nickel(Ni), though Co have more atomic mass than Ni (Law was arrangement of atom in a period considering increasing atomic maas).

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