Physics - Mock Test 14

Question 131

A light year is a measure of

A) Speed B) Velocity C) Distance D) Time

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A light-year is a unit of length equal to just under 10 trillion kilometres (or about 6 trillion miles). As defined by the International Astronomical Union (TAU), a light-year is the distance that light travels in a vacuum in one Julian year. Note that the lightyear is a measure of distance (rather than, as is sometimes misunderstood, a measure of time).

Question 132

Let [ÃŽ0 ] denote the dimensional formula of the permittivity of vacuum. If M = mass, L = length, T = time and A = electric current, then

A) A B) B C) C D) D

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Question 133

The empirical atom model was given by

A) J. J. Thomson B) Rutherford C) Niels Bohr D) Sommerfeld

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Question 134

The first model of atom was proposed by

A) Hans Geiger B) Rutherford C) J.J. Thomson D) E. Goldstein

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Question 135

The Lyman transitions involve

A) largest changes of energy B) smallest changes of energy C) largest changes of potential energy D) smallest changes of potential energy

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Question 136

In a hydrogen atom, which of the following electronic transitions would involve the maximum energy change

A) n = 2 to n = 1 B) n = 3 to n = 1 C) n = 4 to n = 2 D) n = 3 to n = 2

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Question 137

The Balmer series for the H-atom can be observed

A) if we measure the frequencies of light emitted when an excited atom falls to the ground state B) if we measure the frequencies of light emitted due to transitions between excited states and the first excited state C) in any transition in a H-atom D) None of these

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Question 138

Which of the following series in the spectrum of hydrogen atom lies in the visible region of the electromagnetic spectrum

A) Paschen series B) Balmer series C) Lyman series D) Brackett series

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Question 139

When hydrogen atom is in its first excited level, it’s radius is

A) four times, it ground state radius B) twice times, it ground state radius C) same times, it ground state radius D) half times, it ground state radius.

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Question 140

When hydrogen atom is in its first excited level, it’s radius is

A) four times, it ground state radius B) twice times, it ground state radius C) same times, it ground state radius D) half times, it ground state radius.

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