Assertion: The molar mass of H 2 ​ O is 18 g mol⁻¹. Reason: The atomic masses of hydrogen and oxygen are 1 and 16 respectively.

📘 Assertion–Reason Analysis

🔵 Assertion

The molar mass of H₂O is 18 g mol⁻¹.

This statement is True. The molar mass of a compound is calculated by adding the atomic masses of all the atoms present in its formula.

H₂O = (2 × H) + (1 × O)

🟠 Reason

The atomic masses of hydrogen and oxygen are 1 and 16 respectively.

This statement is True. We use these atomic masses to calculate the molar mass of H₂O.

H = 1 g mol⁻¹

O = 16 g mol⁻¹

🧮 Calculation

Molar Mass of H₂O

= (2 × 1) + (1 × 16)

= 2 + 16

= 18 g mol⁻¹

🎬 H₂O Molecular Mass Animation

H H O → 18 g mol⁻¹

2 hydrogen atoms + 1 oxygen atom give the molar mass of H₂O.

🔗 Relationship Between Assertion & Reason

H = 1    O = 16 → (2 × 1) + 16 → 18 g mol⁻¹

Therefore, the Reason correctly explains the Assertion.

✅ Final Answer

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

🎯 Key Concept

Molar Mass of H₂O

= (2 × 1) + 16

= 18 g mol⁻¹