ATOMIC STRUCTURE

CHEMISTRY
Target
IIT-JEE 2023 D P P

COURSE: JEE Nurture No. 4

DPP-4

(de-Borglie's Relation, Uncertainty Principle and Photoelectric Effect)

Multiple Choice Questions with only one correct answer
1. If the intensity of light falling on a metal is B 9. The De-Broglie wavelength of 10 – 17 m, then the C
doubled then: momentum (kg ms –1) of a particle will be:
(A) The energy of photon is doubled (A) 13.25 x 10–17 (B) 26.5 x 10–7
(B) The number of photon is doubled (C) 6.625 x 10–17 (D) 3.3125 x 10–7
(C) The energy of photon is halved 10. The de-Broglie wavelength associated with a C
(D) The number of photon is halved particle of mass 1 mg moving with a velocity of
2. What is number of waves made by an electron A 10 ms-1 is:
moving in 4th orbit. (A) 6.63 x10–29 m (B) 6.63 x 10–31 m
–34
(C) 6.63 x 10 m (D) 6.63 x 10–22 m
(A) 4 (B) 3 (C) 5 (D) 6
3. Suppose a photon of frequency  causes D 11. If uncertainty in the position of an electron is D
photoelectric emission from a surface with a zero, the uncertainty in its momentum would be:
threshold frequency o, little lower than , what is (A) Zero (B) < h/4  (C) > h/4  (D) infinite
the de-Broglie wavelength  of the photoelectron 12. If the Planck’s constant h = 6.6 x 10–34Js, the de- C
of maximum kinetic energy in terms of ∆ =-o Broglie wavelength of a particle having
(A) ∆ = h/zm (B) ) ∆ = h/ momentum 3.3 x 10–24 kg ms –1 will be:
1 (A) 0.02 Ǻ (B) 0.5 Ǻ
 1 1  mc 2  h  2
(C)     (D)  =   (C) 2 Ǻ (D) 500 Ǻ
0   h  2 m  13. An electron in a hydrogen atom in its ground A
4. The dissociation energy of H2 is 430.53 kJmol–1. A state absorbs twice its ionisation energy. What is
If H2 is dissociated by illuminating with the the wavelength of the emitted electron?
radiation of wavelength 253.7nm, the fraction of (A) 3.32 x 10–10 m (B) 33.2 x 10–10 m
the radiant energy which will be converted into (C) 0.33 x 10 –10 m (D) 0.33 x 10–10 m
kinetic energy is given by: 14. The uncertainty in position of an electron moving D
(A) 8.53% (B) 2.33% (C) 1.3% (D) 100%
at 40% of the velocity of light with an uncertainty
5. The difference of energy of photon absorbed and A of velocity of 10-2 m is:
work function is: (A) 48.3 x 10–9 m (B) 4.4 x 10–9 m
(A) Kinetic energy (B) Potential energy (C) 0.44 x 10 m–9 (D) 4.83 x 10–9 m
(C) Ionisation potential (D) Electron affinity 15. The uncertainty in momentum of an electron is 1 A
6. Heisenberg’s principal is not applicable to: A x 10-5 kg–m/s. The uncertainty in its position will
(A) Stationary particles (B) Electron be (h = 6.62 × 10- 34 kg –m2/s)
(C) Microscope particles (D) All of the above. (A) 5.27 x 10–30 m (B) 1.05 x 10–26 m
(C) 1.05 x 10 m–28 (D) 5.27 x 10–28 m
7. Which of the following relate to light as wave D
motion, to light as a stream of particles or to 16. An electron, a proton and an alpha particle have A
both? kinetic energies of 16E, 4E and E respectively.
(A) Diffraction (B) Interference What is the quanlitative order of their De-broglie
(C) Photoelectric effect (D) E = mc2 wavalength?
8. The uncertainty in the position of an electron D (A) e > p > a (B) p > a > e
(mass = 9.1 × 10 – 28 g) moving with a velocity of (C) p > e > a (D) a > e > p
3.0 × 104 cm s -1 accurate up to 0.011% will be 17. The final speed of the electron accelerated form A
(use h/4π in uncertainty expression where h = rest of mass m and charge e through a potential
6.626 x 10 – 27 ergs) difference V in vacuum is
(A) 1.92 cm (B) 7.68 cm (A) (eV / 2m (B)2eV/m
(C) 5.76 cm (D) 3.84 cm
(C) 2eV / m (D) eV / m

Ranjeet Shahi M.Tech, Ph.D IIT-DELHI 1

Allen Career Institute
dare to pursue your dream to become an achiever
 "Daly Practice Paper “Atomic Structure”
18. If E1, E2, and E3 represent respectively the kinetic 24. Photoelectric emission is observed from a surface B
energies of an electron, an alpha particle and a for frequencies v1 and v1 of the incident radiation
proton respectively each having same de-Broblie (v1 > v1). If the maximum K.E. of the
wavelength then. photoelectrons in two cases are in ratio 1:k then
(A) E1 > E3 > E2 (B) E2 >E3>E1 the threshold frequency v0 is given by
(C) E1 > E2 > E3 (D) E1=E2=E3 v2  v1 Kv1  v2
(A) (B)
19. A photon of energy hv is absorbed by a free A K 1 K 1
electron of a metal having work–function  < hv. B Kv2  v1 v2  v1
(C) (D)
Choose the correct option(s). K 1 K
(A) The electron is sure to come out. 25. A particle A moving with a certain velocity has a B
(B) The electron is sure to come out with kinetic de–Broglie wavelength of 1Å. If particle B has
energy hv -  mass 25% of that A and velocity 75% of that of
(C) Either the electron does not come out or it A, the  of B will be approximately
comes out with a kinetic energy hv-  (A) 1Å (B)5.3Å (C) 0.2Å (D) 3Å
(D) It may come out with a kinetic energy less 26. If the radius of first Bohr orbit is x, then de- B
than and equal to hv-  Broglie wavelength of electron in 3rd orbit is
20. In photoelectric effect work function of any metal A nearly
is 2.5eV. The most energetic emitted electrons (A) 2 x (B) 6 x (C) 9x (D) x/3
are stopped by the potential of –1.5 volt then 27. Minimum accelerating potential (volts) needed to A
(A) energy of incident photons is 4eV excite a yellow line in the spectrum of an electron
(B) energy of incident photons is 1eV tube containing some vapours (  =310 nm) is
(C)Photoelectric current increases when we use (A) 1.5 x 10-5 (B) 4 x 10-5
photons of high frequency (C) 6.410 -19 (D) 210-15
(D) none of the above
28. Heisenberg’s principal is not applicable to: A
21. With the help of following graph calculate K.E. A (A) Stationary particles (B) Electron
corresponding to =2000A˚ (C) Microscope particles (D) All of the above
29. The uncertainty in the position of an electron D
(mass = 9.1 x 10–28 g) moving with a velocity of
3.0 x 104 cm s-1 accurate up to 0.011% will be
(use h/4π in uncertainty expression where h =
6.626 x 10– 34 Js)
(A) 1.92 cm (B) 7.68 cm
(C) 5.76 cm (D) 3.84 cm
30. The uncertainty in position of an electron moving D
(A) 171600 J/mole (B) 2500 J/mol at 40% of the velocity of light with an uncertainty
(C) 6106 J /mol (D) None of velocity of 10-2 m is:
(A) 48.3 x 10–9 m (B) 4.4 x 10–9 m
22. If the energy of ground state of H atom is E, then C (C) 0.44 x 10 m–9 (D) 4.83 x 10–9 m
the velocity of photoelectron liberated when a
photon of energy Ep strikes a stationary Li2+ ion Answer
in ground state is (1)B (2)A (3)D (4)A (5)A (6)A
3E p 2( E p  E ) (7)D (8)D (9)C (10)C (11)D (12)C
(A) (B) (13)A (14)D (15)A (16)A (17)A (18)A
m m (19)AB (20)A (21)A (22)C (23)B (24)B
2( E p  9 E ) 2( E p  4 E ) (25)B (26)B (27)A (28)A (29)D (30)D
(C) (D)
m m “Success is the sum of small efforts, repeated day in
and day out.”
23. de-Broglie wavelength of electron in an excited H- B
like species is 222 pm. The minimum energy
required to remove this electron out of system is:
(A) 13.6 eV (B) 30.6 eV
(C) 54.6 eV (D) 122.4 eV

Ranjeet Shahi M.Tech, Ph.D IIT-DELHI 2

Allen Career Institute
dare to pursue your dream to become an achiever