MCQs of Planck quantum theory

1. MULTIPLE CHOICE QUESTIONS PLANCK QUANTUM THEORY It discusses MCQs with answers on Planck's quantum theory topic. It includes a short explanation that depicts the answers.

2. Q.1. Which nature of light is explained by Planck's quantum theory? a. Particle c. Object b. Wave d. Magnetic Answer: Particle Explanation: Planck's quantum theory proves the particle nature of light experimentally with the photoelectric effect and black body radiation. Jayam chemistry adda Jayam chemistry adda

3. Q.2. What do you mean by 'quantum' in Planck's quantum theory? a. A bundle of frequency of light c. A packet of energy d. Another name for electromagnetic radiation b. A chunk of light energy Answer: A packet of energy Explanation: According to Planck's quantum theory, the quantum is the minimum amount of energy emitted or absorbed by the body. Jayam chemistry adda Jayam chemistry adda

4. Q.3. Who discovered quantum theory? a. James Clerk Maxwell c. Isaac Newton b. Max Planck d. Heinrich Hertz Answer: Max Planck Explanation: In 1900, Max Planck explained the particle nature of light with his theory known as Planck's quantum theory. It solved the mysteries of black body emissions in the ultraviolet region. Jayam chemistry adda Jayam chemistry adda

5. Q.4. What is the name for a bundle of light energy in Planck’s quantum theory? a. Proton c. Positronium b. Photon d. Protium Answer: Photon Explanation: Photon denotes the bundle of light energy in Planck’s quantum theory. Jayam chemistry adda Jayam chemistry adda

6. Q.5. Which of the following expresses the particle nature of light? c. Photoelectric effect a. Interference b. Diffraction d. Spin orbit coupling Answer: Photoelectric effect Explanation: The photoelectric effect explains the particle nature of light. The photoelectric effect is the minimum frequency of light required to eject an electron from the metal surface. Since the photoelectric effect restricts to a particular electron on the metal surface, it explains the particle character. Jayam chemistry adda Jayam chemistry adda

7. Q.6. Planck's quantum theory is based on____________ a. Classical physics c. Atomic physics b. Electromagnetic theory d. Quantum mechanics Answer: Quantum mechanics Explanation: It is the basic theory of quantum mechanics. And it paved the way for the dual character of matter. Previously, scientists considered that matter and energy were two unrelated separate entities with unique behavior. Later, they accepted the dual behavior of matter and light proposed by de-Broglie. Jayam chemistry adda Jayam chemistry adda

8. To own the e-book on MCQs of Planck's quantum theory, kindly visit our e-book store at; https://kameswariservices201831.myinstamojo.com/ product/3448340/mcqs-of-planck-quantum-theory- with-answers

9. Q.7. What is Planck's quantum equation? a. E=hv c. E=hf b. E=mvr d. E= ncq Answer: E=hv Explanation: Planck's quantum formula shows the relationship of a photon with the frequency of light. According to it, the energy of light radiation varies directly with its frequency. So, an increase in the frequency of emitted or absorbed light radiation increases its energy. And vice versa. Jayam chemistry adda Jayam chemistry adda

10. Q.8. Which of the following is not a postulate of Planck’s quantum theory? c. A body cannot emit or absorb whole number multiples of energy. a. A body emits discrete packets of energy discontinuously. d. The minimum energy absorbed by the body is a quantum. b. The magnitude of energy of a photon varies directly with its frequency. Answer: A body cannot emit or absorb whole number multiples of energy Explanation: According to Planck’s quantum theory, a body can accept or release whole number multiples of quantum. For example- an object can give or take 1hν, 2hν, or 3hν, nhν units of energy. Energy in fractions of a quantum can neither emitted nor absorbed. For example- an object cannot transmit 1/2hν, 3/2hν, or 5/4hν units of energy. Jayam chemistry adda Jayam chemistry adda

11. Q.9. Planck's quantum theory contradicts which of the following law? c. Pauli's exclusion law a. Newton's motion law b. Rayleigh-Jeans law d. Wien's displacement law Answer: Rayleigh-Jeans law Explanation: The theoretical assumption of Rayleigh-Jeans law deviated from practical observations of black body emissions at the shorter wavelengths. The assumption of erratic energy emissions by the black body solved the heavy energy change in the ultraviolet region as predicted by Rayleigh-Jeans law leading to ultraviolet catastrophe. Jayam chemistry adda Jayam chemistry adda

12. Q.10. What is the relationship between the energy and frequency of light in Planck’s quantum theory? a. E=hc c. E=hcv b. E=hv d. E=hf Answer: E=hv Explanation: It shows the energy of a photon varies directly with its frequency. So, low- frequency radiations contain low energy. Conversely, high energetic radiations possess high frequencies. It indicates the frequency of radiation expresses its associated energy. Jayam chemistry adda Jayam chemistry adda

13. Q.11. Who explained the photoelectric effect following quantum theory? a. Rayleigh & Jeans c. Isaac Newton b. Heinrich Hertz d. Gustav Kirchhoff Answer: Isaac Newton Explanation: Isaac Newton supported the quantum nature of light proposed by Max Planck and explained the photoelectric effect. When an incident light strikes the metal surface, two things will happen. A part of a photon's energy removes the electron from the metal surface by overcoming its binding energy. It is called threshold energy. The remaining photon's energy helps in the motion of the photoelectron. Jayam chemistry adda Jayam chemistry adda

14. Q.12. What is the shape of the black body curve following Max Planck quantum predictions? a. Straight line parallel to X- axis c. Straight line parallel to Y-axis b. Inverted U-shaped curve d. Distorted circular Answer: Inverted U-shaped curve Explanation: At a particular temperature, the emissive power of the black body initially increases with an increase in wavelength. At a particular wavelength, the emissive power shows the peak value. Beyond the peak wavelength, the emissive power of the body drops slowly with a further rise in wavelength. It gives an inverted U-shaped curve for the black bodies. Jayam chemistry adda Jayam chemistry adda

15. Q.13. When did Planck put forward his quantum model? a. 1900 c. 1885 b. 1913 d. 1864 Answer: 1900 Explanation: In 1900, Max Planck explained the particle nature of light with his theory known as Planck's quantum theory. Jayam chemistry adda Jayam chemistry adda