Question

Mendeleev periodic table was discarded because of the fact that

• A. Many elements have several isotopes.
• B. Noble gases form many compounds.
• C. Atomic weight are not always whole number
• D. Some groups stand divided into sub-groups.

Answer 1

The correct option is A

Many elements have several isotopes.

Answer: Option (A)

Explanation of correct option.

Mendeleev's periodic table had some limitations also

1. Position of hydrogen in Mendeleev's periodic table was not fixed.
2. Since, Classification in Mendeleev's periodic table was based on atomic mass, therefore, it cannot accommodate isotopes.
3. Wrong order of some elements could not be explained.

Explanation of Incorrect option.

Since Mendeleev's periodic table couldn't accommodate the position of isotopes. Therefore, option (A) is correct and other options are incorrect.