The wavelength of kα, X-rays produced by an X-ray tube 0.76Å. The atomic number

⇦

⇨

The wavelength of kα, X-rays produced by an X-ray tube 0.76Å. The atomic number of the anode material of the tube is

Options

(a) 20
(b) 60
(c) 41
(d) 80

Correct Answer:

41

Explanation:

Given, wavelength, λ(kα) = 0.76 Å = 0.76 × 10⁻¹° m
Moseley’s empirical formula for Kα X-rays when adapted to Bohr model is given by,
hʋ(Kα) = (3/4) × 13.6 (Z-1)² eV
hc/λ(kα) = (3/4) × 13.6 × 1.6 × 10⁻¹⁹ (Z-1)² J
[Since, 1 eV = 1.6 × 10⁻¹⁹ J]
We know that, h = 6.626 × 10⁻³⁴ J-s and c = 3 × 10⁸ ms⁻¹
Substituting the values in the above equations, we get
(6.626 × 10⁻³⁴ × 3 × 10⁸)/(0.76 × 10⁻¹°) = 16.08 × 10⁻¹⁹ (Z-1)²
26.15 × 10⁻¹⁶ = 16.03 × 10⁻¹⁹ (Z-1)²
1.63 × 10³ = (Z-1)² ⇒ 16.3 × 10² = (Z-1)²
⇒ Z – 1 = 40.4 ⇒ Z = 40.4 + 1 ≈ 4.1

Related Questions:

1. In a vessel, the gas is at a pressure P. If the mass of all the molecules
2. A body is thrown with a velocity of 9.8 m/s making angle of 30° with the horizontal
3. A coil has an area of 0.05 m² and it has 800 turns. It is placed perpendicularly
4. In a diffraction pattern due to a singleslit of width a, the first minimum is observed
5. If n₁, n₂ and n₃ are the fundamental frequencies of three segments into which a string

Topics: Atoms and Nuclei (136)
Subject: Physics (2479)

---

Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score

18000+ students are using NEETLab to improve their score. What about you?

Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.

---

Share this page with your friends