Question

According to Mendeleev's periodic table, one element whose atomic mass is greater than that of nickel is placed before nickel. Name the element.

• A. Copper
• B. Iron
• C. Zinc
• D. Cobalt

Answer 1

The correct option is D Cobalt

Mendeleev arranged the periodic table on the basis of relationship between the atomic masses of elements and their physical and chemical properties.

According to Mendeeev's periodic table chemical and physical properties of elements should repeat after certain interval.He arranged the elements in increasing order of atomic mass but there were certain cases which show anomalous position of elements. For example,cobalt was placed before nickel despite having atomic mass greater than that of nickel.

Mendeleev focused more on the periodic properties rather than atomic mass of elements.