In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of 3 .15 × 10 - 18 J from the radiations of 600 nm , calculate the number of photons received by the detector.

Velocity of radiation ( c ) = 3 × 10 8 ms - 1 Planck’s constant ( h ) = 6 .62 × 10 - 34 Js Given: Wavelength ( λ ) = 600 nm Energy received by the photons = 3 .15 × 10 - 18 J E = hc λ Where, λ = Wavelength of radiation h = Planck’s constant c = Velocity of radiation Substituting the values in the given expression of E: E = 6 .62 × 10 - 34 Js 3 × 10 8 ms - 1 600 × 10 - 9 = 3 .313 × 10 - 19 J Energy of one photon = 3 .313 × 10 - 19 J Number of photons received with 3 .15 × 10 - 18 J of energy = 3 .15 × 10 - 18 J 3 .313 × 10 - 19 J = 9.5 ≈ 10

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An ion with mass number $37$ possesses one unit of negative charge. If the ion contains $11.1 %$ more neutrons than the electrons, find the symbol of the ion.

Important Questions on Structure of Atom

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11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.44

An ion with mass number

56

contains

3

units of positive charge and

30.4

% more neutrons than electrons. Assign the symbol to this ion.

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Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.45

Arrange the following type of radiations in increasing order of frequency: (a) radiation from microwave oven (b) amber light from traffic signal (c) radiation from FM radio (d) cosmic rays from outer space and (e) X-rays.

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Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.46

Nitrogen laser produces a radiation at a wavelength of

337 .1 nm .

If the number of photons emitted is

5.6 \times 10^{24},

calculate the power of this laser.

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11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.47

Neon gas is generally used in the sign boards. If it emits strongly at

616 nm,

calculate (a) the frequency of emission, (b) distance traveled by this radiation in

30 s

2 J

of energy.

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11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.48

In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of

3 .15 \times 10^{- 18} J

from the radiations of

600 nm,

calculate the number of photons received by the detector.

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11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.49

Lifetimes of the molecules in the excited states are often measured by using pulsed radiation source of duration nearly in the nano second range. If the radiation source has the duration of

2

ns

and the number of photons emitted during the pulse source is

2 .5 \times 10^{15},

calculate the energy of the source.

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11th CBSE

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Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.5

The longest wavelength doublet absorption transition is observed at

589

and

589.6 nm .

Calculate the frequency of each transition and energy difference between two excited states.

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11th CBSE

IMPORTANT

Textbook for Class XI Chemistry Part I>Chapter 2 - Structure of Atom>EXERCISES>Q 2.51

The work function for caesium atom is $1 .9 eV$ . Calculate (a) the threshold wavelength and (b) the threshold frequency of the radiation. If the caesium element is irradiated with a wavelength $500 nm,$ calculate the kinetic energy and the velocity of the ejected photoelectron.

An ion with mass number 37 possesses one unit of negative charge. If the ion contains 11.1% more neutrons than the electrons, find the symbol of the ion.

Important Questions on Structure of Atom

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An ion with mass number $37$ possesses one unit of negative charge. If the ion contains $11.1 %$ more neutrons than the electrons, find the symbol of the ion.