1. Choose the correct statement. The work function of a metal
1) is same for all metals 2) is different for different metals
3) is small for heavy elements
4) depends upon the frequency of the incident radiation.
2. A metal whose work function is 3.31 eV is illuminated by light of wavelength 3 × 10-7m. What is the threshold frequency for the photoelectric emission?
1) 0.8 × 1015 Hz 2) 1.6 × 1015 Hz 3) 2.4 × 1015 Hz 4) 3.2 × 1015 Hz
3. The threshold wavelength for a certain metal surface is 330 A°. What is the maximum KE of the photoelectrons released, by a radiation of 1100A° wavelength?
1) 1 eV 2) 2 eV 3) 3 eV 4) No photoelectrons are emitted
4. The photoelectric current in a photoelectric cell depends upon
1) Nature of the metal used as the emitter
2) Wavelength of the incident light
3) intensity of the incident light
4) all the above parameters
5. The wavelength associated with a photon of energy E is - (Take c as the velocity of light in air)
1) hc/E 2) h/CE 3) c/hE 4) hcE
6. Light of wavelength 3500 A° is incident on two metals X and Y whose work functions are 4.2 eV and 1.9 eV respectively. Which metal will emit photoelectrons?
1) metal X 2) metal Y 3) Both X and Y 4) neither X nor Y
7. A proton, when accelerated through a potential difference of V volts, has a wavelength λ associated with it. If an α -particle is to have the same wavelength λ, it must be accelerated through a potential difference of - (in volts)
1) 4V 2) V/4 3) 8V 4) V/8
8. The de Broglie wavelength of a neutron, when its Kinetic energy is K, is λ. What will be its wavelength when its Kinetic energy is 4K?
1) 2λ 2) λ/2 3) 4λ 4) λ/4
9. Moving with the same velocity, which of the following has the longest de Broglie wavelength?
1) proton 2) neutron 3) β-particle 4) α-particle
10. The slope of the graph of the frequency of incident light versus the stopping potential for given metallic surface is
1) h 2) e/h 3) h/e 4) 1
11. If λ is the de Broglie wavelength for a proton accelerated through a potential difference of 100 V, then the de-Broglie wavelength for an α-particle accelerated through the same potential difference is
1) λ/√2 2) λ/√1 3) λ/2√2 4) 2√2.λ
12. The energy required to excite a hydrogen atom from n=1 to n=2 energy state is 10.2 eV. What is the wavelength of the radiation emitted by the atom when it goes back to its ground state?
1) 1020°A 2) 1120°A 3) 1220°A 4) 1320°A
13. The total energy of the electron in the first excited state of hydrogen is -3.4 eV. Then the Kinetic energy of the electron in this state is
1) -3.4 eV 2) +3.4 eV 3) −6.8 eV 4) +6.8 eV
14. The wavelength of the first line in Balmer series in the hydrogen spectrum is λ. Then the wavelength of the second line is
1) 3λ/16 2) 5λ/36 3) 20λ/27 4) 3R/37
15. The orbital speed of the electron in the ground state of hydrogen is V. Then its orbital speed when it is excited to the energy state of -3.4 eV is
1) V/2 2) V/4 3) V/8 4) 2V
16. The energy released by the fission of one Uranium atom is 200 Mev. Then the number of fissions per second required to produce 3.2 W of power is
1) 107 2) 1010 3) 1011 4) 1012
17. The ratio of wavelengths of the longest wavelength lines in the Lyman and Balmer series of hydrogen spectrum is
1) 5/27 2) 7/29 3) 29/7 4) 27/5
18. During a negative B-decay
1) an atomic electron is ejected
2) an electron which is already present within the nucleus is ejected
3) a neutron in the nucleus decays emitting an electron
4) a part of the binding energy of the nucleus is converted into an electron.
19. The radioactive decay of an element X to elements Y and B is represented by the equation.
ZXA →Z+1YA →Z-1BA-4 →Z-1BA-4
Then the sequence of the emitted radiations is .....
1) α, β, γ 2) β, α, γ 3) α, γ, β 4) γ, β, α
20. What is the number of α and β particles emitted in the following radioactive decay?
90X200→ 80 Y168
1) 6 and 8 2) 8 and 6 3) 8 and 8 4) 6 and 6
21. The half life of a radioactive substance is 30 days. The time taken for 3/4 of its original mass to disintegrate is .....
1) 45 days 2) 60 days 3) 75 days 4) 90 days
22. In an n-p-n transistor circuit, the collector current is 10 mA. If 80% of the electrons emitted reach the collector, then
1) emitter current will be 7.5 mA
2) emitter current will be 12.5 mA
3) base current will be 3.5 mA
4) base current will be 2.0 mA
23. The combination of gates shown in the figure yields ......
1) AND gate 2) NOT gate 3) NAND gate 4) NOR gate
24. Whenever a hydrogen atom emits a photon in the Balmer series
1) It need not emit any more photon
2) It may emit another photon in the paschen series
3) It must emit another photon in the Lyman series
4) It may emit another photon in the Balmer series
25. Two electrons are revolving around a nucleus at distances r and 4r. Then the ratio of their periods is.....
1) 1:4 2) 4:1 3) 1:8 4) 8:1
26. When a hydrogen atom is raised from the ground state to fifth state, then .....
1) both KE and PE increase 2) both KE and PE decrease
3) PE increases and KE decreases 4) PE decreases and KE increases
27. Which of the following parameters are the same for all hydrogen-like atoms and ions in their ground states?
1) radius of the orbit 2) speed of the electron
3) energy of the atom 4) orbital angular momentum of the electron
28. Difference between n th and (n+1)th Bohr's radius of hydrogen atom is equal to (n-1)th Bohr's radius. Then the value of n is ........
1) 1 2) 2 3) 3 4) 4
29. The truth table given is for-
1) NOR gate 2) AND gate 3) NAND gate 4) OR gate
30. The combination of gates shown below produces .....
1) AND gate 2) XOR gate 3) NOR gate 4) NAND gate
31. If the radius of an orbit is r and the velocity of electron in it is V, then the frequency of electron in that orbit is
1) 2πrV 2) 2π/rV 3) Vr/2π 4) V/2πr
32. If R is the Rydberg constant for hydrogen, then the wave number of the first line in the Lyman series .......
1) R/2 2) 2R 3) R/4 4) 3R/4
33. If, λ1 and λ2 are the wave lengths of the first members of the Lyman and Paschen series, respectively, then λ1:λ2 is --
1) 1:3 2) 1:30 3) 7:50 4) 7:108
34. A stationary hydrogen atom of mass M emits a photon corresponding to the first line of Lyman series. If R is Rydberg's constant, then the velocity acquired by the atom is......
1) Rh/M 2) Rh/2M 3) Rh/4M 4) 3Rh/4M
35. The force acting on the electron in a hydrogen atom depends on the principal quantum number as .....
1) F ∝ n2 2) F ∝ 1/n2 3) F ∝ n4 4) F ∝ 1/n4
36. In hydrogen atom, the shortest wavelength in Balmer series is λ. Then the shortest wavelength in Brackett series will be .....
1) 2λ 2) 4λ 3) 9λ 4) 16λ
37. Two ideal junction diodes D1 and D2 are connected to a battery as shown in the figure. The current supplied by the battery is
1) 0.25A 2) 0.50A 3) 0.75A 4) 1A
38. The angular momentum of an electron in an orbit is quantized because it is a necessary condition for the compatibility with
1) the wave nature of electron 2) particle nature of electron
3) Pauli’s exclusion behaviour 4) none of the above
39. In Bohr’s model of hydrogen atom, the ratio of the kinetic energy to the total energy of the electron in nth quantum state is
1) -1 2) +1 3) -2 4) +2
Answers: 1-2; 2-1; 3-4; 4-4; 5-1; 6-2; 7-4; 8-2; 9-3; 10-2; 11-3; 12-3; 13-2; 14-3; 15-1; 16-3; 17-1; 18-3; 19-2; 20-2; 21-2; 22-2; 23-1; 24-3; 25-3; 26-3; 27-4; 28-4; 29-3; 30-4; 31-4; 32-4; 33-4; 34-4; 35-4; 36-2; 37-2; 38-1; 39-1.
