Question

17. State modern periodic law. Write down the limitations of
Mendeleev's periodic table.​

Answer 1

Answer:position of rare earth metals were not correct.

Position of isotopes we're not correct

Explanation:

Answer 2

Modern periodic law states that, 'The properties of elements are a periodic function of their atomic number.'

Limitation's of Medeleev's Periodic Table are:

• Position of Hydrogen => Position of hydrogen in the perodic table is uncertain because hydrogen is placed in the first group with Alkali metals.
• Position of isotopes => Isotopes haven't been given separate place in the periodic table.
• Cause of periodicity => Mendeleev could not explain the cause of periodicity.
• Separation of similar elements => Some dissimilar elements have been placed together.

Hope it helps...