JEE Chemistry Structure of Atoms MCQs B

Question: Which of the scientist were able to prove that atom is no longer non-divisible?

• a) Michael Faraday
• b) Chadwick
• c) Dalton
• d) Thomson

Answer: Michael Faraday

Question: Which of the following is never true for cathode rays ?

• a) They are electromagnetic waves
• b) They possess kinetic energy.
• c) They produce heat
• d) They produce mechanical pressure

Answer: They are electromagnetic waves

Question: Cathode rays are deflected by

• a) by both
• b) an electric field only
• c) magnetic field only
• d) by none

Answer: by both

Question: Which of the following statement is not correct about the characteristics of cathode rays?

• a) Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube
• b) Characteristics of cathode rays do not depend upon the material of electrodes in cathode ray tube
• c) They travel in straight line in the absence of an externalelectrical or magnetic field
• d) They start from the cathode and move towards the anode

Answer: Characteristics of cathode rays depend upon the nature of gas present in the cathode ray tube

Question: Which of the following statements about the electron is incorrect?

• a) The mass of electron is equal to the mass of neutron
• b) It is negatively charged particle
• c) It is a basic constituent of all atoms
• d) None of these

Answer: The mass of electron is equal to the mass of neutron

Question: While performing cathode ray experiments, it was observed that there was no passage of electric current under normal conditions. Which of the following can account for this observation ?

• a) Air is a poor conductor of electricity under normal conditions
• b) None of the above
• c) Carbon dioxide is present in air
• d) Dust particles are present in air

Answer: Air is a poor conductor of electricity under normal conditions

Question: Which is not true with respect to cathode rays?

• a) Move with speed same as that of light
• b) Charged particles
• c) A stream of electrons
• d) Can be deflected by magnetic fields

Answer: Move with speed same as that of light

Question: What is the optimum conditions required to study the conduction of electricity through gases

• a) Low pressure and high voltage
• b) High pressure and high voltage
• c) High pressure and low voltage
• d) Low pressure and low voltage

Answer: Low pressure and high voltage

Question: In discharge tube experiment stream of negatively charged particles travel from

• a) cathode to anode
• b) Electrons does not travel
• c) anode to cathode
• d) None of these

Answer: cathode to anode

Question: Millikan performed an experiment method to determine which of the following ?

• a) Charge of the electron
• b) Mass of the electron
• c) e/m ratio of electron
• d) None of these

Answer: Charge of the electron

Question: The discovery of neutron became very late because

• a) neutrons are chargeless
• b) neutrons are present in nucleus
• c) neutrons are fundamental particles
• d) all of the above

Answer: neutrons are chargeless

Question: Which is correct statement about proton ?

• a) neutron
• b) positron
• c) None of these
• d) proton

Answer: neutron

Question: When beryllium is bombarded with alpha particles (Chadwick’s experiment) extremely penetrating radiations, Which cannot be deflected by electrical or magnetic field are given out. These are :

• a) A beam of neutrons
• b) Alpha rays
• c) A beam of protons
• d) A beam of neutrons and protons

Answer: A beam of neutrons

Question: Neutron is discovered by

• a) Chadwick
• b) Yukawa
• c) Rutherford
• d) Dalton

Answer: Chadwick

Question: Suppose beam containing all three fundamental subatomic particles are allowed to pass through an electric field as shown in figure. The subatomic particles detected at three points A, B and C on the screen respectively are ?

• a) Electrons, neutrons, protons
• b) Protons, neutrons, electrons
• c) Electrons, protons, neutrons
• d) Neutrons, protons, electrons

Answer: Electrons, neutrons, protons

Question: Which of the following properties of atom could be explained correctly by Thomson Model of atom?

• a) Overall neutrality of atom
• b) Spectra of hydrogen atom
• c) Position of electrons, protons and neutrons in atom
• d) Stability of atom

Answer: Overall neutrality of atom

Question: Arrange the following in terms of penetrating power.

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Which of the rays are not deflected by the electric and magnetic field ?

• a) Both
• b)

  

• c)

  

• d) None of these

Answer: Both

Question:

• a) nucleus
• b) electrons
• c) protons
• d) neutrons'

Answer: nucleus

More Questions......................................

Question: When atoms are bombarded with alpha particles, only, a few in million suffer deflection, others pass out undeflected. This is because

• a) the nucleus occupies much smaller volume compared to the volume of the atom
• b) there is only one nucleus and large number of electrons
• c) the force of attraction between alpha particle and oppositely charged electrons is very small
• d) the force of repulsion on the moving alpha particle is small

Answer: the nucleus occupies much smaller volume compared to the volume of the atom

Question:

• a) all positive ions are deposited at small part
• b) all negative ions are deposited at small part
• c) proton moves around the electron
• d) neutrons are charged particles.

Answer: all positive ions are deposited at small part

Question: Rutherford’s experiment which established the nuclear model of the atom used a beam of

• a) helium nuclei, which impinged on a metal foil and got scattered
• b) helium atoms, which impinged on a metal foil and got scattered
• c) Both
• d) None of these

Answer: helium nuclei, which impinged on a metal foil and got scattered

Question: Which of the following scientists explained his model on the basis of centrifugal force ?

• a) Rutherford
• b) Dalton
• c) Thomson
• d) Millikan

Answer: Rutherford

Question: The number of neutrons in dipositive zinc ion with mass number 70 is

• a) 40
• b) 36
• c) 34
• d) 38

Answer:  40

Question:

• a) 20
• b) 40
• c) 19
• d) 18

Answer: 20

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:

• a) 89, 142, 89
• b) 89, 231, 89
• c) 89, 89, 242
• d) 89, 71, 89

Answer: 89, 142, 89

Question: An element has atomic number 11 and mass number 24. What does the nucleus contain?

• a) 11 protons, 13 neutrons
• b) 11 protons, 13 neutrons, 13 electrons
• c) 13 protons, 11 neutrons
• d) 13 protons, 11 electrons

Answer: 11 protons, 13 neutrons

Question: The number of electrons and neutrons of an element is 18 and 20 respectively. Its mass number is

• a) 38
• b) 17
• c) 2
• d) 37

Answer: 38

Question:

• a) Z decreases by 2, A decreases by 4
• b) Z decreases by 2, A increases by 4
• c) Z increases by 2, A increases by 4.
• d) Z increases by 2, A decreases by 4

Answer: Z decreases by 2, A decreases by 4

Question: Nucleons are

• a) neutrons + protons
• b) only neutrons
• c) neutrons + protons + electrons
• d) neutrons + electrons

Answer: neutrons + protons

Question: Atoms with same mass number but different atomic numbers are called

• a) isobars
• b) None of these
• c) isotopes
• d) isochores

Answer: isobars

Question:  Which of the following pairs will have same chemical properties ?

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: What is the difference between two species if one has atomic mass = 14 and atomic number = 7 whereas the other has atomic mass = 14 and atomic number = 6 ?

• a) All of these
• b) Protons
• c) Neutrons
• d) Electrons

Answer: All of these

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: If the wavelength of the electromagnetic radiation is increased to thrice the digital value, then what will be the percent change in the value of frequency of the electromagnetic radiation.

• a) Decreases by 66%
• b) Decreases by 33%
• c) Increases by 33%
• d) Increases by 66%

Answer:  Decreases by 66%

Question:  Which is the correct schematic representation of the graph of black body radiation.

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question: The ideal body, which emits and absorbs radiations of all frequencies, is called a black body and the radiation emitted by such a body is called

• a) black body radiation
• b) None of these
• c) white body radiation
• d) black body emission

Answer: black body radiation

Question: Which one of the following is not the characteristic of Planck’s quantum theory of radiation ?

• a) The energy is not absorbed or emitted in whole number or multiple of quantum
• b) Radiation is associated with energy
• c) Radiation energy is not emitted or absorbed continuously but in the form of small packets called quanta
• d) This magnitude of energy associated with a quantum is proportional to the frequency.

Answer: The energy is not absorbed or emitted in whole number or multiple of quantum

Question: Which of the following is related with both wave nature and particle nature ?

• a) 

  

• b)

  

• c) Interference
• d) Diffraction

Answer:

Question: The value of Planck's constant is 6.63 × 10^–34 Js. The velocity of light is 3.0 × 108 m s^–1. Which value is closest to the wavelength in nanometers of a quantum of light with frequency of 8 × 10¹⁵ s^–1 ?

• a) 4 × 10¹
• b) 2 × 10^–25
• c) 3 × 10⁷
• d) 5 × 10^–18

Answer: 4 × 10¹

Question: In the photo-electron emission, the energy of the emitted electron is

• a) smaller than the incident photon
• b) same as than of the incident photon
• c) greater than the incident photon
• d) proportional to the intensity of incident photon

Answer: smaller than the incident photon

Question: When a metal surface is exposed to solar radiations

• a) The emitted electrons have energy less than a maximum value of energy depending upon frequency of incident radiations
• b) The emitted electrons have energy less than maximum value of energy depending upon intensity of incident radiation
• c) The emitted electrons have zero energy
• d) The emitted electrons have energy equal to energy of photons of incident light

Answer: The emitted electrons have energy less than a maximum value of energy depending upon frequency of incident radiations

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: In continous spectrum light of _(i_)_ wavelength is deviated the _ii_

• a) (i) = longest, least
• b) (i) = shortest, most
• c) (ii) = shortest, least
• d) (i) = longest, most

Answer: (i) = longest, least

Question: Which of the following statements do not form a part of Bohr’s model of hydrogen atom ?

• a) The position and velocity of the electrons in the orbit cannot be determined simultaneously
• b) Electrons revolve in different orbits around the nucleus
• c) The electron(s) in the orbit nearest to the nucleus has the lowest energy
• d) Energy of the electrons in the orbits are quantized

Answer: The position and velocity of the electrons in the orbit cannot be determined simultaneously

Question: An electron from one Bohr stationary orbit can go to next higher orbit

• a) by absorption of electromagnetic radiation of particular frequency
• b) by absorption of any electromagnetic radiation
• c) by emission of electromagnetic radiation
• d) None of these

Answer: by absorption of electromagnetic radiation of particular frequency

Question: For a Bohr atom angular momentum M of the electron is (n = 0, 1, 2, .....)

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: According to Bohr's theory, the angular momentum of an electron in 5th orbit is

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: In Bohr’s model, atomic radius of the first orbit is y, the radius of the 3rd orbit, is

• a) 9y
• b) y
• c) y / 3
• d) 3y

Answer: 9y

Question: The radius of 1st Bohr’s orbit for hydrogen atom is ‘r’. The radius of second Bohr’s orbit is

• a) 4r
• b) 4r²
• c) r³
• d) None of these

Answer: 4r

Question: The third line of the Balmer series, in the emission spectrum of the hydrogen atom, is due to the transition from the

• a) fifth Bohr orbit to the second Bohr orbit
• b) fourth Bohr orbit to the first Bohr orbit
• c) sixth Bohr orbit to the third Bohr orbit
• d) seventh Bohr orbit to the third Bohr orbit

Answer: fifth Bohr orbit to the second Bohr orbit

Question: Which one of the following pairs is not correctly matched ?

• a) Bohr-Isotopes
• b) J.H. Chadwick-Neutron
• c) J.J. Thomson-Electron
• d) Rutherford-Proton

Answer: Bohr-Isotopes

Question: If r is the radius of the first orbit, the radius of nth orbit of H-atom is given by

• a) rn²
• b) rn
• c) r² n²
• d) None of these

Answer: rn²

Question: The radius of hydrogen atom in the ground state is 0.53 Å. The radius of Li²⁺ ion (atomic number = 3) in a similar state is

• a) 0.17 Å
• b) 0.53 Å
• c) 0.265 Å
• d) 1.06 Å

Answer: 0.17 Å

Question: The energy of an electron in the n^th Bohr orbit of hydrogen atom is

• a)

  

• b)

  

• c)

  

• d) None of these

Answer:

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: In a hydrogen atom, if energy of an electron in ground state is 13.6. eV, then that in the 2nd excited state is

• a) 1.51 eV
• b) 6.04 eV
• c) 3.4 eV
• d) 13.6 eV.

Answer: 1.51 eV

Question: The energy of an electron in second Bohr orbit of hydrogen atom is

• a) –5.44 × 10^–19J
• b) –5.44 × 10^–19cal
• c) –5.44 × 10^–19eV
• d) –5.44 × 10^–19kJ

Answer: –5.44 × 10^–19J

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The ionisation potential of a hydrogen atom is –13.6 eV. What will be the energy of the atom corresponding to n = 2.

• a) – 3.4 eV
• b) – 1.7 eV
• c) – 6.8 eV
• d) –2.7 eV

Answer: – 3.4 eV

Question: The line spectrum of He⁺ ion will resemble that of

• a) hydrogen atom
• b) helium atom
• c) Li⁺ ion
• d) lithium atom

Answer: hydrogen atom

Question: What does negative sign in the electronic energy for hydrogen atom convey.

• a) The energy of electron in the atom is lower than the energy of a free electron of rest
• b) The energy of electron in the atom is lower than the energy of a free electron in motion
• c) The energy of electron decreases as it moves away from nucleus
• d) Energy of electron

Answer: The energy of electron in the atom is lower than the energy of a free electron of rest

Question: In which of the following Bohr’s stationary state, the electron will be at maximum distance from the nucleus ?

• a) Vth
• b) IInd
• c) Ist
• d) IIIrd

Answer: Vth

Question: The wavelength of the radiation emitted, when in a hydrogen atom electron falls from infinity to stationary state 1, would be (Rydberg constant = 1.097×10⁷ m^–1)

• a) 91 nm
• b) 406 nm
• c) 192 nm
• d) 9.1×10^–8 nm

Answer: 91 nm

Question: The frequency of radiation emitted when the electron falls from n = 4 to n = 1 in a hydrogen atom will be (Given : ionization energy of H=2.18 ×10^–18J atom–1and h = 6.625 × 10^–34 J s )

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Which of the following transitions of electrons in the hydrogen atom will emit maximum energy ?

• a)

  

• b)

  

• c)

  

• d) all will emit same energy

Answer:

Question: The first emission line of hydrogen atomic spectrum in the Balmer series appears is (R = Rydberg constant)

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: According to the Bohr theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon ?

• a) n = 6 to n = 5
• b) n = 6 to n = 1
• c) n = 5 to n = 4
• d) n = 5 to n = 3

Answer: n = 6 to n = 5

Question:  The wavelength (in cm) of second line in the Lyman series of hydrogen atomic spectrum is (Rydberg constant = R cm^–1)

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The shortest wavelength in hydrogen spectrum of Lyman series when R_H = 109678 cm^–1 is

• a) 911.7Å
• b) 1215.67Å
• c) 1002.7Å
• d) 1127.30Å

Answer: 911.7Å

Question:

• a)

  

• b)

  

• c)

  

• d) All the above are correct

Answer:

Question: Bohr model can explain

• a) spectrum of any atom or ion containing one electron only
• b) the spectrum of hydrogen atom only
• c) the spectrum of hydrogen molecule
• d) the solar spectrum

Answer: spectrum of any atom or ion containing one electron only

Question: Which of the following statements do not form a part of Bohr’s model of hydrogen atom ?

• a) The position and velocity of the electrons in the orbit cannot be determined simultaneously
• b) Electrons revolve in different orbits around the nucleus
• c) The electron in the orbit nearest the nucleus has the lowest energy
• d) Energy of the electrons in the orbits are quantized

Answer: The position and velocity of the electrons in the orbit cannot be determined simultaneously

Question: Bohr’s theory can be applied to which of the following ions.

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Bohr’s model is not able to account for which of the following.

• a) Spectrum of neutral helium atom.
• b) Stability of atom
• c) Energy of free electron at rest
• d) Calculation of radii of the stationary states

Answer: Spectrum of neutral helium atom.

Question: If electron, hydrogen, helium and neon nuclei are all moving with the velocity of light, then the wavelength associated with these particles are in the order

• a) Electron > hydrogen > helium > neon
• b) Electron > helium > hydrogen > neon
• c) Electron < hydrogen < helium < neon
• d) Neon < hydrogen < helium < electron

Answer:  Electron > hydrogen > helium > neon

Question: The de Broglie wavelength of a tennis ball of mass 60 g moving with a velocity of 10 metres per second is approximately

• a) 10^–33 metres
• b) 10^–16 metres
• c) 10^–31 metres
• d) 10^–25 metres

Answer: 10^–33 metres

Question: If the energy difference between the ground state of an atom and its excited state is 4.4 × 10^–4 J, the wavelength of photon required to produce the transition

• a) 4.52 × 10^–12 m
• b) 1.13 × 10^–12 m
• c) 2.26 × 10^–12 m
• d) 4.52 × 10^–16 m

Answer: 4.52 × 10^–12 m