The eyes of a reptile pass a visual signal to the brain when the visual receptors are struck by photons of wavelength 850 nm If an energy of 3 . 15 × 10 - 14 J is required to trip the signal, what is the minimum number of photons that must strike the receptor h = 6 . 6 × 10 - 34 ?

The energy of one photon is given by E = h c λ = 6 . 6 × 10 - 34 × 3 × 10 8 850 × 10 - 9 = 2 . 3 × 10 - 19 J The energy required to trip signal = 3 . 15 × 10 - 14 J n × E = E total photons that strike the receptor are The number of photons required is n = 3 . 15 × 10 - 14 2 . 3 × 10 - 19 = 1 . 37 × 10 5 photons

If the velocity of the electron in first orbit of H atom is 2 . 18 × 10 6 ms - 1 , what is its value in third orbit?

The velocity of an electron in n th orbit of H - atom is given by, v = 1 4 πε 0 2 πZe 2 nh On substituting the values of constants, 1 4 πε 0 = 9 × 10 9 Nm 2 C - 2 , h = 6 . 626 × 10 - 34 Js , e = 1 . 6 × 10 - 19 C We get the reduced formula, v = 2 . 18 × 10 6 × Z n Z = 1 , n = 3 v = 2 . 18 × 10 6 × 1 3 m / s v = 7 . 26 × 10 5 m / s

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One quantum is absorbed per gaseous molecule of ${Br}_{2}$ for converting into $Br$ atoms. If light absorbed has wavelength $5000 Å$ , calculate energy required in $kJ {mol}^{- 1}$ .

Important Questions on Structure of Atom

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 10

The eyes of a reptile pass a visual signal to the brain when the visual receptors are struck by photons of wavelength

850 nm

If an energy of

3.15 \times 10^{- 14} J

is required to trip the signal, what is the minimum number of photons that must strike the receptor

(h = 6.6 \times 10^{- 34}) ?

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 12

If a light with frequency of

4.0 \times 10^{16}

Hz

emitted photoelectrons with double the kinetic energy as are emitted by the light of frequency

2.5 \times 10^{16} Hz

from the same metal surface then what is the threshold frequency of the metal?

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 13

Which state of the triply ionised beryllium,

{Be}^{3 +}

, has the same radius as that of the ground state of hydrogen atom?

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 14

If the velocity of the electron in first orbit of

H

atom is

2.18 \times 10^{6} {ms}^{- 1},

what is its value in third orbit?

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 15

Consider Bohr's theory for hydrogen atom. The magnitude of angular momentum, orbit radius and velocity of the electron in

n^{th}

energy state in a hydrogen atom are

l, r

and

v

respectively. Find out the value of

{}^{'}x^{'},

if product of

v, r

and

l (vrl)

is directly proportional to

n^{x} .

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 16

Find the ratio of the time period of

2^{nd}

Bohr orbit of

{He}^{+}

and

4^{th}

Bohr orbit of

{Li}^{2 +} .

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 18

A hydrogen sample is prepared in a particular excited state. Photons of energy $2.55 eV$ get absorbed into the sample to take some of the electrons to a further excited state $B .$ Find orbit numbers of the states $A$ and $B .$ Given the allowed energies of hydrogen atom:

$E_{1} = - 13.6 eV, E_{2} = - 3.4 eV, E_{3} = - 1.5 eV, E_{4} = - 0.85 eV, E_{5} = - 0.54 eV$

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 19

A single electron atom has nuclear charge $+ Ze$ where $Z$ is atomic number and $e$ is electronic charge. It requires $42.7 eV$ to excite the electron from the second Bohr's orbit to third Bohr's orbit. Find :

(a) the atomic number of element.

(b) the energy required for transition of electron from third to fourth orbit.

(d) the kinetic energy of electron in first Bohr's orbit.

One quantum is absorbed per gaseous molecule of Br2 for converting into Br atoms. If light absorbed has wavelength 5000 Å, calculate energy required in kJ mol-1.

Important Questions on Structure of Atom

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One quantum is absorbed per gaseous molecule of ${Br}_{2}$ for converting into $Br$ atoms. If light absorbed has wavelength $5000 Å$ , calculate energy required in $kJ {mol}^{- 1}$ .