# Atomic Structure

1. The electrons identified by quantum numbers n and l
a) n = 4, l = 1           b) n = 4, l = 0            c) n = 3, l = 2
d) n = 3, l = 1 can be placed in order of increasing energy as
1) d < b < c < a             2) b < d < a < c            3) a < c < b < d             4)  c < d  < b <  a

2. Consider the ground states of Cr atom (Z = 24). The numbers of electrons with the azimuthal quantum numbers l = 1 and 2 are, respectively
1) 12,              4  2) 12, 5              3) 16, 4              4) 16, 5

3. Which of the following combination of statements is true regarding the interpretation of the atomic orbitals?
a) An electron in an orbital of high angular momentum stays away from the nucleus than an electron in the orbital of lower angular momentum.
b) For a given value of the principal quantum number, the size of the orbit is inversely to the azimuthal quantum number.
c) According to the wave mechanics, the ground state angular momentum is h equal to  . h/2π
d) The plot of  ψ vs r for various azimuthal quantum numbers shows peak shifting towards higher r value.
1) b, c           2) a, d            3) a, b              4) a, c

4. In a Bohr’s model of an atom, when an electron jumps from n = 1 to n = 3, how much energy will be emitted or absorbed?
1) 2.389 × 10−12 ergs           2) 0.238 × 10−10 ergs             3) 2.15 × 10−11 ergs            4) 0.1936 × 10−10 ergs

5. The radius of hydrogen atom in the ground state is 0.53 A°. The radius of Li2+ ion (atomic number = 3) in a similar state is
1) 0.53 A°             2) 1.06 A°             3) 0.17 A°          4) 0.265 A°

6. The orbital angular momentum of a p - electron is given as 7. The de Broglie wave length of a particle with mass 1g and velocity 100 m/s is
1) 6.63 × 10−35 m            2) 6.63 × 10−34 m          3) 6.63 × 10−33 m          4) 6.65 × 10−35 m

8. Which one of the following expressions represent the electron probability function (D)?
1) 4πrdrψ2          2) 4πr2drψ              3) 4πr2drψ2               4) 4πrdrψ

9. Bohr’s postulate that mvr = nh/2π is proved mathematically by
1) Pauli’s exclusion principle
2) de Broglie wave nature of the electron
3) Heisenberg’s uncertainty principle
4) Sommerfeld theory

10. The correct  set of four quantum numbers for the valence electrons of rubidium atom (Z = 37) is
1) 5, 0, 0, + 1/2          2) 5, 1, 0, + 1/2           3) 5, 1, 1, + 1/2           4) 5, 0, 1, + 1/2

11. Which of the following is the energy of a possible  excited state of hydrogen?
1) + 13.6 eV          2) − 6.8 eV                3) − 3.4 eV             4) + 6.8 eV

12. A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference V esu. If e and m are charge and mass of an electron respectively, then the value of h/λ (where λ is wavelength associated with electron wave) is given by 13. The energy required to break one mole of Cl − Cl bonds in Cl2 is 242 kJmol−1. The longest wavelength of light capable of breaking a single Cl − Cl bond is (C = 3 × 108 ms−1 and NA = 6.02 × 1023 mol−1)
1) 494 nm           2) 594 nm            3) 640 nm            4) 700 nm

14. According to Plank’s quantum theory, the correct statements are
a) The vibrating particle in the black body does not emit continuously.
b) Radiation is emitted in the form of small packets called quanta.
c) Energy associated with emitted radiations is inversely proportional to frequency.
d) The emitted radiant energy is propagated in the from of waves
1) a, b, c             2)  b, c              3) a, b, d                4) b, d, c

15.  Based on equation E = −2.178 × 10−18 Certain conclusions are written, which of them is not correct?
1) Equation can be used to calculate the change in energy when the electron changes orbit.
2) For n = 1 the electron has a more negative energy than it does for n = 6, which means that the electron is more loosely bound in the smallest allowed orbit.
3) The negative sign in equation simply means that the energy of electron bound to the nucleus is lower than is would be if the electrons were at the infinite distance from the nucleus.
4) Larger the value of n, the larger is the orbit radius

16. The maximum number of electrons in a sub shell is given by the expression
1) 4l − 2          2) 4l + 2             3) 2l + 2           4) 2n2

17. The number of radial nodes in 3p orbitals are/is
1) one          2) three          3) none            4) two

18. Which of the following pairs of d - orbitals will have electron density along the axes?
1) dz2, dxz           2) dxz, dyz            3) dz2, dx2 − y2          4) dxy, dx2 − y2

19. Consider the following sets of quantum numbers. Which of the following sets of quantum numbers is not possible?
1) i, ii, iii and iv            2) ii, iv and v             3) i and iii                4) ii, iii and iv

20. In an atom, an electron is moving with a speed of 600 m/s with an accuracy of 0.005%. Certainty with which the position of the electron can be located is (h = 6.6 × 10−34 kg m2 s−1, mass of electron, em = 9.1 × 10−31 kg)
1) 5.10 × 10−3 m           2) 1.92 × 10−3 m              3) 3.84 × 10−3 m        4) 1.52 × 10−4 m

Answers: 1-1; 2-2; 3-4; 4-4; 5-3; 6-1; 7-3; 8-3; 9-2; 10-1; 11-3; 12-3; 13-1; 14-3; 15-2; 16-2; 17-1; 18-3; 19-2; 20-2.

Posted Date : 12-04-2021

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గమనిక : ప్రతిభ.ఈనాడు.నెట్‌లో కనిపించే వ్యాపార ప్రకటనలు వివిధ దేశాల్లోని వ్యాపారులు, సంస్థల నుంచి వస్తాయి. మరి కొన్ని ప్రకటనలు పాఠకుల అభిరుచి మేరకు కృత్రిమ మేధస్సు సాంకేతికత సాయంతో ప్రదర్శితమవుతుంటాయి. ఆ ప్రకటనల్లోని ఉత్పత్తులను లేదా సేవలను పాఠకులు స్వయంగా విచారించుకొని, జాగ్రత్తగా పరిశీలించి కొనుక్కోవాలి లేదా వినియోగించుకోవాలి. వాటి నాణ్యత లేదా లోపాలతో ఈనాడు యాజమాన్యానికి ఎలాంటి సంబంధం లేదు. ఈ విషయంలో ఉత్తర ప్రత్యుత్తరాలకు, ఈ-మెయిల్స్ కి, ఇంకా ఇతర రూపాల్లో సమాచార మార్పిడికి తావు లేదు. ఫిర్యాదులు స్వీకరించడం కుదరదు. పాఠకులు గమనించి, సహకరించాలని మనవి.