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Assertion: Lyman series lies in the visible region of electromagnetic spectrum.

Reason: This is because Balmer series also lies in visible region.

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Important Questions on Atoms, Molecules and Nuclei

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IMPORTANT
MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 8
The average life time of a hydrogen atom excited to n=2 state is 10-8 s. The period of revolution of the electron on an average before it jumps to ground state is,
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MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 9
The binding energy per nucleon for H21 and  He42 are 1.1 MeV and 7.1 MeV, respectively. The energy released when two H21 combine to form He42 is,
HARD
MHT-CET
IMPORTANT
MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 12
A hydrogen atom moves with a velocity u and makes a head-on inelastic collision with another stationary hydrogen atom. Both atoms are in the ground state before collision. The minimum value of u if one of them is to be given a minimum excitation energy is,
HARD
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IMPORTANT
MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 13
The magnetic moment by virtue of the orbital motion of an electron in an atom when orbital angular momentum is equal to one quantum unit is,
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MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 16
A material found within the body of an organism trapped in an iceberg had a C146 activity of about 0.144 Bq g-1. C146 activity of the living organism is 0.28 Bq g-1 and its half life 5730 years. The age of the organism would be,
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MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 17

Assertion: Ionisation energy of atomic hydrogen is greater than atomic deuterium.

Reason: Ionisation energy is proportional to reduced mass.

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MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 18
Transitions between three energy levels in a particular atom give rise to three spectral lines of wavelengths in increasing magnitude λ1, λ2 and λ3. Which one of the following equations correctly relates λ1, λ2 and λ3?
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MHT-CET TRIUMPH Physics Multiple Choice Questions Part - 2 Based on Std. XI & XII Syllabus of MHT-CET>Chapter 12 - Atoms, Molecules and Nuclei>Evaluation Test>Q 20

A beam of monochromatic light of wavelength λ ejects photoelectrons from a caesium surface W0=1.9 eV which are made to collide with hydrogen atoms in ground state. The maximum value of λ for which hydrogen atoms may be ionised is

(Take value of h=6.6×10-34 in SI units)