Atomic and Nuclear physics Book Back Questions & Answers
Unit 9 > Physics > Class 12 > Samacheer Kalvi - English Medium
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1. Atomic number of H-like atom with ionization potential 122.4 V for n = 1 is
(a) 1
(b) 2
(c) 3
(d) 4
Correct answer: (c) 3
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2. The ratio between the first three orbits of hydrogen atom is
(a) 1:2:3
(b) 2:4:6
(c) 1:4:9
(d) 1:3:5
Correct answer: (c) 1:4:9
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3. The charge of cathode rays particle is
(a) positive
(b) negative
(c) neutral
(d) not defined
Correct answer: (b) negative
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4. In J.J. Thomson e/m experiment, a beam of electron is replaced by that of muons (particle with same charge as that of electrons but mass 208 times that of electrons). No deflection condition is achieved only if
(a) B is increased by 208 times
(b) B is decreased by 208 times
(c) B is increased by 14.4 times
(d) B is decreased by 14.4 times
Correct answer: (c) B is increased by 14.4 times
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5. The ratio of the wavelengths radiation emitted for the transition from n =2 to n = 1 in Li++, He+ and H is
(a)1: 2: 3
(b) 1: 4: 9
(c) 3:2:1
(d) 4: 9: 36
Correct answer: (d) 4: 9: 36
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6. If the nuclear radius of 27Al is 3.6 fermi, the approximate nuclear radius of 64Cu in fermi is
(a) 2.4
(b) 1.2
(c) 4.8
(d)3.6
Correct answer: (c) 4.8
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7. The mass of a 3 7 Li nucleus is 0.042 u less than the sum of the masses of all its nucleons. The average binding energy per nucleon of 3 7 Li nucleus is nearly
(a) 46 MeV
(b) 5.6 MeV
(c) 3.9MeV
(d)23 MeV
Correct answer: (b) 5.6 MeV
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8. The half-life period of a radioactive element A is same as the mean life time of another radioactive element B. Initially both have the same number of atoms. Then
(a) A and B have the same decay rate initially
(b) A and B decay at the same rate always
(c) B will decay at faster rate than A
(d) A will decay at faster rate than B.
Correct answer: (c) B will decay at faster rate than A