Consider the statements below and identify the correct answer.
Statement-I: Isotopes of all elements posed a challenge to Medeleev's periodic law.
Statement-II: No fixed position can be given to hydrogen in the periodic table.

Correct option is C

The correct answer is: (c) Both statements are correct

Explanation:

• Statement I: True. Isotopes of elements have the same chemical properties but different atomic masses. Since Mendeleev’s periodic law was based on increasing atomic mass, the existence of isotopes sometimes conflicted with his arrangement.
• Statement II: True. Hydrogen shows properties similar to both alkali metals (group 1) and halogens (group 17), so no fixed position can be universally assigned in the periodic table.

Information Booster:

• Hydrogen is placed in group 1 for convenience in modern periodic tables.
• Isotopes were discovered after Mendeleev proposed his table (e.g., Chlorine-35 & Chlorine-37).
• Modern periodic law is based on atomic number, which resolved isotopic inconsistencies.
• Hydrogen has only one electron in the outer shell.
• Mendeleev predicted properties of elements like gallium and germanium despite atomic mass anomalies.