Assertion–Reason Questions Directions: For each question, choose the correct option: A. Both Assertion and Reason are true, and Reason is the correct explanation of Assertion. B. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion. C. Assertion is true, but Reason is false. D. Assertion is false, but Reason is true.

🧪 Assertion–Reason Questions

Directions:
For each question, choose the correct option:

A. Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

B. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

C. Assertion is true, but Reason is false.

D. Assertion is false, but Reason is true.

Assertion (A):
One mole of any substance contains 6.022 × 10²³ particles.

Reason (R):
Avogadro's number represents the number of particles present in one mole of a substance.

✅ Correct Answer: A

Both Assertion and Reason are true, and the Reason correctly explains the Assertion.

Assertion (A):
The molar mass of H₂O is 18 g mol⁻¹.

Reason (R):
H₂O contains two hydrogen atoms and one oxygen atom.

✅ Correct Answer: A

H₂O = (2 × 1) + (1 × 16) = 18 g mol⁻¹. The Reason explains the calculation of molar mass.

Assertion (A):
0.5 mole of a substance contains 3.011 × 10²³ particles.

Reason (R):
One mole contains 6.022 × 10²³ particles.

✅ Correct Answer: A

0.5 × 6.022 × 10²³ = 3.011 × 10²³ particles. Therefore, both statements are true and the Reason explains the Assertion.

Assertion (A):
Molarity changes with temperature.

Reason (R):
Molarity depends on the volume of the solution, and volume can change with temperature.

✅ Correct Answer: A

Molarity = Moles of solute / Volume of solution in litres. Since solution volume may change with temperature, molarity can also change.