Question

Anomalous pair among the following is:

• A. boron - silicon
• B. aluminium - nickel
• C. beryllium - indium
• D. cobalt - nickel

Answer 1

The correct option is D cobalt - nickel

Anomalous pair means the pair of elements where the mass of the first one is higher than the second one. Thus among the given options cobalt-nickel are an anomalous pair. This was one of the drawbacks of Mendeleev's periodic table.

Hence, the correct option is $\text{D}$