Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Physical properties of isotopes of hydrogen are different.
Reason R: Mass difference between isotopes of hydrogen is very large.
In the light of the above statements, choose the correct answer from the options given below:

• A. A is false but R is true
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. Both A and R are true and R is the correct explanation of A

Answer 1

The Correct Option is D

To solve this question, let's analyze both the assertion and the reason given, and determine their correctness along with the relationship between them:

Assertion A: Physical properties of isotopes of hydrogen are different.

Reason R: Mass difference between isotopes of hydrogen is very large.

1. Understanding Assertion A:
   • Isotopes are variants of the same chemical element that have the same number of protons, but different numbers of neutrons. For hydrogen, the isotopes are Protium, Deuterium, and Tritium.
   • Physical properties, such as density, boiling point, and melting point, can differ between isotopes due to their mass difference.
   • Example: Deuterium is about twice as heavy as Protium, which affects its physical properties.
   • Therefore, Assertion A is true.
2. Understanding Reason R:
   • The mass of isotopes is determined by the number of neutrons. Protium has 0 neutrons, Deuterium has 1, and Tritium has 2.
   • Due to the heavy hydrogen nucleus in Deuterium and even heavier in Tritium, the mass difference between these isotopes compared to Protium is substantial.
   • The large mass difference is responsible for the differing physical properties.
   • Therefore, Reason R is true and indeed explains Assertion A's statement.
3. Evaluating the Relationship:
   • Since both the assertion and reason are true and the reason correctly explains why the assertion is true, the correct explanation is that such a mass difference is responsible for the variation in physical properties.
   • This aligns with the option: Both A and R are true and R is the correct explanation of A.

Thus, the correct answer is: Both A and R are true and R is the correct explanation of A.