At what atomic number would a transition from n = 2 to n = 1 energy level result in emission of photon of λ = 3 × 10 - 8 m .

According to Rydberg's formula, 1 λ = RZ 2 1 n 1 2 - 1 n 2 2 Substituting the values of known quantities, 1 3 × 10 - 8 = 1 . 097 × 10 7 × Z 2 1 1 2 - 1 2 2 Z 2 = 4 3 × 10 - 8 × 1 . 097 × 10 7 × 3 Z 2 = 4 Z = 2 Hence, the given transition will result from helium atom which has atomic number 2 .

The uncertainty in position and velocity of the particle are 0 . 1 nm and 5 . 27 × 10 - 24 ms - 1 , respectively then find the mass of the particle. h = 6 . 625 × 10 - 34 Js

Heisenberg uncertainty principle explains that the position and momentum of a particle cannot be precisely calculated simultaneously. An attempt to precisely calculate any one of the two, leads to an increase in uncertainty of the other. ∆ x . ∆ p = h 4 π Momentum is the product of mass of the particle and its velocity. So, ∆ x . m ∆ v = h 4 π 0 . 1 × 10 - 9 × m × 5 . 27 × 10 - 24 = 6 . 625 × 10 - 34 4 π m = 6 . 625 × 10 - 34 6 . 625 × 10 - 33 kg m = 0 . 1 kg Hence, mass of the particle is 0 . 1 kg .

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Calculate the frequency of light emitted for an electron transition from the sixth to second orbit of the hydrogen atom. In what region of the spectrum does this light occur?

Important Questions on Structure of Atom

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 24

At what atomic number would a transition from

n = 2

n = 1

energy level result in emission of photon of

λ = 3 \times 10^{- 8} m .

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 25

In a container a mixture is prepared by mixing of three samples of hydrogen, helium ion

({He}^{+})

and lithium ion

({Li}^{2 +}) .

In sample all the hydrogen atoms are in

1^{st}

excited state and all the

{He}^{+}

ions are in third excited state and all the

{Li}^{2 +}

ions are in fifth excited state. Find the total number of spectral fines observed in the emission spectrum of such a sample, when the electrons return back up to the ground state.

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 26

An electron in a

H

-atom in its ground state absorbs

1.5

times as much energy as the minimum required for its escape

(13.6 eV)

from the atom. What is wavelength of the emitted electron?

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 27

Deduce the condition when the de-Broglie wavelength associated with an electron would be equal to that associated with a proton, if a proton is

1836

times heavier than an electron.

HARD

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 28

An electron, which is practically at rest, is initially accelerated through a potential difference of

100

volts. It then has a de Broglie wavelength

= λ_{1} Å .

It then gets retarded through

19

volts and then has a wavelength

λ_{2} Å .

Further retardation through

32

volts changes the wavelength to

λ_{3} Å .

What is

\frac{λ_{3} - λ_{2}}{λ_{1}} ?

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 29

If an electron having kinetic energy

2 eV

is accelerated through the potential difference of

2

Volt. Then calculate the wavelength associated with the electron.

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 30

The uncertainty in position and velocity of the particle are

0.1 nm

and

5.27 \times 10^{- 24} {ms}^{- 1},

respectively then find the mass of the particle.

(h = 6.625 \times 10^{- 34} Js)

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Alpha Question Bank for Engineering: Chemistry>Chapter 2 - Structure of Atom>Exercise-1>Q 35

Given below are the sets of quantum numbers for given orbitals. Name these orbitals.

$(a) \begin{matrix} n = 3 \\ l = 1 \end{matrix}$ $(b) \begin{matrix} n = 5 \\ l = 2 \end{matrix}$ $(c)$ $\begin{matrix} n = 4 \\ l = 1 \end{matrix}$ $(d) \begin{matrix} n = 2 \\ l = 0 \end{matrix}$ $(e)$ $\begin{matrix} n = 4 \\ l = 2 \end{matrix}$

Calculate the frequency of light emitted for an electron transition from the sixth to second orbit of the hydrogen atom. In what region of the spectrum does this light occur?

Important Questions on Structure of Atom

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