1. Millikan oil drop apparatus is used for measuring
Ans: (3)
Explanation: Used for measuring charge 'e' on electron.
2. Television picture tubes are ------ tubes and Television pictures result due to ---- -- on the television screen.
1) anode ray, fluorescence 2) cathode ray, fluorescence
3) anode ray, phosphorescence 4) cathode ray, phosphorescence
Ans: (2)
Explanation: Due to cathode ray and fluorescence.
3. Consider the ground state of Cr atom (Z = 24). The number of electrons with the azimuthal quantum numbers l = 1 and l = 2 are respectively
1) 16, 5 2) 16, 4 3) 12, 4 4) 12, 5
Ans: (4)
Explanation: l = 1 = p subshell 6 in 2p + 6 in 3p = 12
l = 2 = d subshell 5 in 3d = 5.
4. The uncertainity in velocity of an electron, if the uncertainity in its position is of the order of 1 A° is
1) 5.8 × 105 m sec-1 2) 5.8 × 105 cm sec-1 3) 5.8 A° 4) 5.8 pm
Ans: (1)
Explanation:
5. Photoelectric emission is observed from a surface for frequencies υ1 and υ2, the kinetic energies are in the ratio 1 : k, then the threshold frequency υ0 is given by
1) υ2 - υ1/k 2) υ2 - υ1/ k - 1 3) kυ2 - υ1/ k - 1 4) kυ1 - υ2/ k - 1
Ans: (4)
Explanation:
6. The threshold frequency υ0 for a metal is 7 × 1014 s-1. The kinetic energy of electron hits the metal with the frequency of the radiation υ = 1 × 1015 s-1 is
1) 1.99 × 10-19 K.J. 2) 1.99 × 10-19 k.cal 3) 1.99 × 10-19 J 4) 1.99 × 10-19 cal
Ans: (3)
Explanation: K.E. = h(υ - υo) = 6.626 × 10-34 Js (1 × 1015 s-1 - 7 × 1014 s-1)
= 1.99 × 10-19 J.
7. The orbital angular momentum of an electron revolving in a 'd'orbital is
Ans: (2)
Explanation:
8. The minimum and maximum values of wavelength in the Lyman series of a H atom are respectively.
1) 91.2 nm, 121.5 nm 2) 912 nm, 1215 nm
3) 41.2 nm, 102.6 nm 4) 364.3 nm, 564.3 nm
Ans: (1)
Explanation:
9. Maximum number of electrons in an orbital with the quantum numbers n = 4, m = 0, l = 2 are
1) 10 2) 0 3) 2 4) 1
Ans: (3)
Explanation: n = 4, l = 2, m = 0 means the orbital is 4dz2. It can have maximum of 2 electrons.
∵ n + l values for 3d, 4s, 3p and 3s are 5, 4, 4, 0 respectively.
10. Correct order of filling of electrons (increasing order of energy) having quantum numbers
1) b > c > a > d 2) c > b > a > d 3) d < a < c < b 4) b > c = a > d
Ans: (3)
11. Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength 3978 A°. The work function W0 is
1) O J 2) 5 cal 3) 9.4 × 10-19 J 4) 5 × 10-19 J
Ans: (4)
Explanation:
12. Correct statements among the following are
a) Solution of Schrodinger wave equation gives E and ψ.
b) Solution of Schrodinger wave equation gives all the quantum numbers.
c) 
is total energy operator.
d) Schrodinger wave equation describes the motion of an electron in three dimentional space.
1) a, b, c 2) a, c, d 3) a, b, d 4) all are correct
Ans: (2)
Explanation: The solution of Schrodinger wave equation gives principal, azimuthal and magnetic quantum numbers but not spin quantum number.
13. The energy of 1 mole of photons of radiation whose frequency is 5 × 1014 Hz is approximately
1) 3.3 × 10-19 J 2) 3.3 K.J. 3) 200 K.J. mol-1 4) 200 J mol-1
Ans: (3)
Explanation: E = N. h.ν = 6.023 × 1023 × 6.626 × 10-34 × 5 × 1014 = 200 KJ mol-1.
14. The wave number of 1st line in Balmer series of Hyderogen is 15,200 cm-1. The wave number of 1st line in Balmer series of Be+3 is
1) 5.4 × 105 cm-1 2) 2.43 × 105 cm-1 3) 3.43 × 105 cm-1 4) 4.43 × 105 cm-1
Ans: (2)
Explanation:
15. The angular and spherical nodes in 3p are respectively
1) 1, 1 2) 0, 1 3) 2, 1 4) 1, 2
Ans: (1)
Explanation: Angular nodes (nodal planes) = l = 1 for p orbital.
Spherical nodes (nodes) = n - l - 1 = 3 - 1 - 1 = 1.
16. If the ionization enthalpy of H atom is 13.6 e.V., the energy required to excite it from ground state to the next higher state is
1) 3.4 e.V. 2) 10.2 e.V. 3) 12.1 e.V. 4) 1.5 e.V.
Ans: (2)
Explanation:
17. Atomic radius of the order of 10-8 cm and nuclear radius is of the order of 10-13 cm. The fraction of atom is occupied by nucleus is
1) 10-26 2) 10-16 3) 10-21 4) 10-15
Ans: (4)
Explanation:
18. The momentum of radiation of wavelength 1.656 nm is
1) 4 × 10-24 kg m sec-1 2) 4 × 10-25 kg m sec-1
3) 4 × 10-24 g cm sec-1 4) 4 × 10-25 g cm sec-1
Ans: (2)
Explanation:
19. In an atom, an electron is moving with a speed of 600 m/s with an accuracy of 0.005%. Certainity with which the position of the electron can be located is
1) 3.84 × 10-3 m 2) 5.1 × 10-3 m 3) 1.92 × 10-3 m 4) 1.52 × 10-4 m
Ans: (3)
Explanation:
20. Name of the series and region of the spectrum when the emission transition starts from the orbit having radius 1.9044 nm and ends at 0.8464 nm.
1) 6 to 4, Bracket series 2) 5 to 2, Balmer series
3) 7 to 3, Paschen series 4) 9 to 5, Pfund series
Ans: (1)
Explanation:
21. Symbol of the orbit for which the radius is 13.2 A°
1) K 2) L 3) O 4) M
Ans: (3)
Explanation:
22. The distance travelled by the radiation of Neon gas in 30 sec if it emits at 616 nm
1) 3 × 108 m 2) 9 × 109 m 3) 3 × 108 cm 4) 9 × 109 cm
Ans: (2)
Explanation:
23. The lowest effective nuclear charge experienced by the electrons of an orbital in Bromine atom is
1) 1s 2) 2p 3) 3d 4) 4p
Ans: (4)
Explanation: As the 4p electrons are at greater distance from the nucleus, electrons of 4p experience the lowest Zeff.
24. The ratio of K.E. : P.E. : T.E. is
1) +1 : -2 : -1 2) -1 : -2: +1 3) 1 : 2 : 1 4) -1 : +2 : -1
Ans: (1)
Explanation:
25. 1s7 configuration for Nitrogen is the violation of
1) Hund's rule 2) Aufbau principle
3) Pauli's exclusion principle 4) All the above
Ans: (3)
Explanation: Violation of Pauli's exclusion principle.
