Option (ii) is the correct choice. Both statements are scientifically true, but the equality of protons and electrons explains electrical neutrality rather than providing the fundamental reason why discovering subatomic constituents clarified atomic architecture.
Assertion (A): The discovery of subatomic particles helped in understanding the atomic structure. Reason (R): The number of electrons is equal to the number of protons in an atom. Choose the correct option: (i) Both A and R are true and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, but R is false. (iv) A is false, but R is true.
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Option (ii) is the correct choice. Assertion A is true because discovering electrons, protons and neutrons explained internal organization, chemical behavior and bonding. Reason R is also true because an atom contains equal counts of protons and electrons, ensuring neutrality. However, statement R simply describes atomic electrical balance and does not serve as the complete scientific explanation for how subatomic discoveries unveiled overall atomic structure.
For more NCERT Solutions of Class 9 Science Exploration Chapter 8 Journey Inside the Atom Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-8/