Verified Solution • 2025–26 Session moderate

Q1.14: NCERT Physics - Part 1 UNITS AND MEASUREMENT 1.14 Solution: The unit of length convenient on the atomic scale is known as…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students frequently mis‑read 1 Å as $10^{-9}$ m or omit the $10^{-10}$ factor, which makes the atomic volume off by three orders of magnitude; always write $1\,\text{Å}=10^{-10}\,$m and keep the exponent through the cubic conversion. Also remember the given "size" of 0.5 Å refers to the radius, not the diameter, otherwise the volume will be eight times too large.

The unit of length convenient on the atomic scale is known as an angstrom and is denoted by �: 1 � = 10___ m. The size of a hydrogen atom is about 0.5 �. What is the total atomic volume in m_ of a mole of hydrogen atoms?

Step-by-Step Verified Solution

**Answer:** 3.16×10−7 m33.16 \times 10^{-7} \text{ m}^3. **Step-by-Step Explanation:** Radius of hydrogen atom r=0.5 �=0.5×10−10 mr = 0.5 \text{ �} = 0.5 \times 10^{-10} \text{ m}. Volume of one atom = 43πr3=43π(0.5×10−10)3=5.24×10−31 m3\frac{4}{3}\pi r^3 = \frac{4}{3}\pi (0.5 \times 10^{-10})^3 = 5.24 \times 10^{-31} \text{ m}^3. For 1 mole: V=6.022×1023×5.24×10−31=3.16×10−7 m3V = 6.022 \times 10^{23} \times 5.24 \times 10^{-31} = 3.16 \times 10^{-7} \text{ m}^3.

All Questions in this Chapter

Q1.1 Q1.2 Q1.3 Q1.4 Q1.5 Q1.6 Q1.7 Q1.8 Q1.9 Q1.10 Q1.11 Q1.12 Q1.13 Q1.14 Q1.15 Q1.16 Q1.17

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