मराठी
कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान इयत्ता ११

The Radius of the Shortest Orbit in a One-electron System is 18 Pm. It May Be - Physics

Advertisements
Advertisements

प्रश्न

The radius of the shortest orbit in a one-electron system is 18 pm. It may be

पर्याय

  • hydrogen

  • deuterium

  • He+

  • Li++

MCQ
Advertisements

उत्तर

Li++

The radius of the nth orbit in one electron system is given by
`r_n = (n^2a_0)/Z`

Here, a0 = 53 pm

For the shortest orbit,
n = 1

For hydrogen,
Z = 1

∴ Radius of the first state of hydrogen atom = 53 pm


For deuterium,
Z= 1

∴ Radius of the first state of deuterium atom = 53 pm


For He+,
Z = 2

∴ Radius of He+ atom =`53/2 pm = 26.5 "pm"`


For Li++,
Z = 3

∴ Radius of Li++ atom = `53/3 "pm" = 17.66"pm" ≈ 18 "pm"`

The given one-electron system having radius of the shortest orbit to be 18 pm may be Li++.

The given one-electron system having radius of the shortest orbit to be 18 pm may be Li++.

shaalaa.com
The Line Spectra of the Hydrogen Atom
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 21: Bohr’s Model and Physics of Atom - MCQ [पृष्ठ ३८३]

APPEARS IN

एचसी वर्मा Concepts of Physics Vol. 2 [English] Class 11 and 12
पाठ 21 Bohr’s Model and Physics of Atom
MCQ | Q 10 | पृष्ठ ३८३

संबंधित प्रश्‍न

Classically, an electron can be in any orbit around the nucleus of an atom. Then what determines the typical atomic size? Why is an atom not, say, a thousand times bigger than its typical size? The question had greatly puzzled Bohr before he arrived at his famous model of the atom that you have learnt in the text. To simulate what he might well have done before his discovery, let us play as follows with the basic constants of nature and see if we can get a quantity with the dimensions of length that is roughly equal to the known size of an atom (~ 10−10 m).

(a) Construct a quantity with the dimensions of length from the fundamental constants e, me, and c. Determine its numerical value.

(b) You will find that the length obtained in (a) is many orders of magnitude smaller than the atomic dimensions. Further, it involves c. But energies of atoms are mostly in non-relativistic domain where c is not expected to play any role. This is what may have suggested Bohr to discard c and look for ‘something else’ to get the right atomic size. Now, the Planck’s constant h had already made its appearance elsewhere. Bohr’s great insight lay in recognising that h, me, and e will yield the right atomic size. Construct a quantity with the dimension of length from h, me, and e and confirm that its numerical value has indeed the correct order of magnitude.


Which wavelengths will be emitted by a sample of atomic hydrogen gas (in ground state) if electrons of energy 12.2 eV collide with the atoms of the gas?


When white radiation is passed through a sample of hydrogen gas at room temperature, absorption lines are observed in Lyman series only. Explain.


The minimum orbital angular momentum of the electron in a hydrogen atom is


A hydrogen atom in ground state absorbs 10.2 eV of energy. The orbital angular momentum of the electron is increased by


Let An be the area enclosed by the nth orbit in a hydrogen atom. The graph of ln (An/A1) against ln(n)

(a) will pass through the origin
(b) will be a straight line with slope 4
(c) will be a monotonically increasing nonlinear curve
(d) will be a circle


Ionization energy of a hydrogen-like ion A is greater than that of another hydrogen-like ion B. Let ru, E and L represent the radius of the orbit, speed of the electron, energy of the atom and orbital angular momentum of the electron respectively. In ground state


Find the radius and energy of a He+ ion in the states (a) n = 1, (b) n = 4 and (c) n = 10.


A hydrogen atom emits ultraviolet radiation of wavelength 102.5 nm. What are the quantum numbers of the states involved in the transition?


(a) Find the first excitation potential of He+ ion. (b) Find the ionization potential of Li++ion.


Whenever a photon is emitted by hydrogen in Balmer series, it is followed by another photon in Lyman series. What wavelength does this latter photon correspond to?


A hydrogen atom in state n = 6 makes two successive transitions and reaches the ground state. In the first transition a photon of 1.13 eV is emitted. (a) Find the energy of the photon emitted in the second transition (b) What is the value of n in the intermediate state?


The average kinetic energy of molecules in a gas at temperature T is 1.5 kT. Find the temperature at which the average kinetic energy of the molecules of hydrogen equals the binding energy of its atoms. Will hydrogen remain in molecular from at this temperature? Take k = 8.62 × 10−5 eV K−1.


A hydrogen atom in ground state absorbs a photon of ultraviolet radiation of wavelength 50 nm. Assuming that the entire photon energy is taken up by the electron with what kinetic energy will the electron be ejected?


A hydrogen atom moving at speed υ collides with another hydrogen atom kept at rest. Find the minimum value of υ for which one of the atoms may get ionized.
The mass of a hydrogen atom = 1.67 × 10−27 kg.


When a photon is emitted from an atom, the atom recoils. The kinetic energy of recoil and the energy of the photon come from the difference in energies between the states involved in the transition. Suppose, a hydrogen atom changes its state from n = 3 to n = 2. Calculate the fractional change in the wavelength of light emitted, due to the recoil.


The Balmer series for the H-atom can be observed ______.

  1. if we measure the frequencies of light emitted when an excited atom falls to the ground state.
  2. if we measure the frequencies of light emitted due to transitions between excited states and the first excited state.
  3. in any transition in a H-atom.
  4. as a sequence of frequencies with the higher frequencies getting closely packed.

Positronium is just like a H-atom with the proton replaced by the positively charged anti-particle of the electron (called the positron which is as massive as the electron). What would be the ground state energy of positronium?


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×