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. The radius of a nucleus of mass number A is directly proportional to
2. If L and C denote inductance and capacitance,then the dimensions of L-C are
3. In a mass spectrometer used for measuring the masses of ions, the ions
4. When an input signal 1 is applied to a NOT gate, then its output is
5. A n-p-n transistor is connected in common emitter configuration in a given amplifier.

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