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Can you explain the answer of this question below:The number of radial nodes for 3p orbital is __________.
A:3
B:4
C:2
D:1
The answer is d.

Krishna Iyer answered
► Number of radial nodes = n - 1 – 1
► For 3p orbital, n = 3 – 1 – 1 = 1
► Number of radial nodes = 3 – 1 – 1 = 1. 

The nucleus of a tritium atom, 3H, contains
  • a)
    three protons
  • b)
    three neutrons
  • c)
    two protons and one neutron
  • d)
    two neutrons and one proton
Correct answer is option 'D'. Can you explain this answer?

Hansa Sharma answered
Tritium (3H) is a radioactive isotope of hydrogen. The nucleus decays (by emitting an electron and an antineutrino), changing from a triton (one proton and two neutrons) to a 3He nucleus (two protons and one neutron).

Electronic configuration of the element having atomic number 24.
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'C'. Can you explain this answer?

Ananya Sarkar answered
atomic no 24 is of Cr. Due to half filled orbital stability it doesnot follow Afbau rule so its configuration is 

Thomson’s plum pudding model explained:
  • a)
     Existence of electrons
  • b)
    Electrical neutrality of an atom
  • c)
    Existence of atoms
  • d)
    Electrons move in fixed circular orbits
Correct answer is option 'B'. Can you explain this answer?

Raghav Bansal answered
Postulates of Thomson’s atomic model
  • An atom consists of a positively charged sphere with electrons filled into it. The negative and positive charge present inside an atom are equal and as a whole, an atom is electrically neutral.
  • Thomson’s model of the atom was compared to plum pudding and watermelon. He compared the red edible part of the watermelon to positively charged sphere whereas the seeds of watermelon to negatively charged particles.

Energy change associated per mole of atoms with an atomic transition giving rise to radiations of  What is the value of x?
    Correct answer is '4'. Can you explain this answer?

    Naina Sharma answered
    Energy = n.hv
    where,
    n = 1 mole or 6.023 × 1023 atoms
    h = 6.626×10-34 J.sec
    v (frequancy) = 1 Hz
    ⇒ E = 6.023 ×1023 × 6.626×10-34 × 1 = 3.91 × 10-10
    so approximately value of x = 4.

    An cation A3+ has 18 electrons. Write the atomic number of A.
    • a)
      15
    • b)
      24
    • c)
      12
    • d)
      21
    Correct answer is option 'D'. Can you explain this answer?

    Lavanya Menon answered
    3+ charge means no of electrons will be 3 less than no. of protons. So no. of protons will be 21. So atomic no. is 21.

    Direction (Q. Nos. 9-11) This section contains 3 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONE or  MORE THANT ONE  is correct.
    Q. Select the correct statement(s).
    • a)
      Electromagnetic radiation is a form of energy consisting of oscillating electric and magnetic fields
    • b)
      Visible light is a form of electromagnetic radiation
    • c)
      The electromagnetic spectrum of sunlight received at the Earth's surface differs from that emitted by the Sun
    • d)
      Ultraviolet radiation is absorbed in the stratosphere by ozone and oxygen
    Correct answer is option 'A,B,C,D'. Can you explain this answer?

    Geetika Shah answered
    Option A: Oscillations travel through space at a velocity of light, thus electromagnetic radiation is in the form of energy E = hv.
    Option B: Radiowaves, microwaves, X-rays, and visible light are part of the Electromagnetic radiation spectrum.
    Option C: Some of the radiations are absorbed in the atmosphere, hence the spectrum differs.
    Option D: Ozone layer absorbs ultraviolet radiation.
    Hence, options A, B, C, and D are correct.

     Whch of the following will have the maximum value of ∆v . ∆x
    • a)
      Cricket ball
    • b)
      Electron
    • c)
      Table
    • d)
      Tennis ball
    Correct answer is option 'B'. Can you explain this answer?

    Geetika Shah answered
    This is accordance with the Heisenberg's uncertainty principle.It states that it is not possible to accurately determine the position and momentum of a microscopic particle such as electron simultaneously.

    Daltons atomic theory could not explain one of the following
    • a)
      Law of multiple Proportions,
    • b)
      Law of conservation of mass
    • c)
      Law of constant composition
    • d)
      Discovery of sub-atomic particles
    Correct answer is option 'D'. Can you explain this answer?

    Om Desai answered
    Dalton’s atomic theory stated that atoms were indivisible. However, the discovery of subatomic particles (such as protons, electrons, and neutrons) disproved this postulate.

    The number of radial nodes for 3p orbital is __________.
    • a)
      3
    • b)
      4
    • c)
      2
    • d)
      1
    Correct answer is 'D'. Can you explain this answer?

    Amrita Kumar answered
    Number of radial nodes = n-1 – 1
    For 3p orbital, n = 3 – 1 – 1 = 1
    Number of radial nodes = 3 – 1 – 1 = 1. 

    Isobars are the atoms with
    • a)
      same atomic number but different number of neutrons
    • b)
      same mass number but different atomic number
    • c)
      same atomic number but different mass number
    • d)
      same number of neutrons but different mass number
    Correct answer is option 'B'. Can you explain this answer?

    Nandini Patel answered
    Isobars are atoms (nuclides) of different chemical elements that have the same number of nucleons. Correspondingly, isobars differ in atomic number (or number of protons) but have the same mass number.

    The nature of positive rays depends on?
    • a)
      The nature of discharge tube.
    • b)
      The nature of residual gas.
    • c)
      The nature of electrode.
    • d)
      All of above
    Correct answer is option 'B'. Can you explain this answer?

    Om Desai answered
    • The nature of positive rays produced in a vacuum discharge tube depends upon the nature of the gas-filled.
    • The positive rays consist of positive ions obtained by removing one or more electrons from gas molecules.

    The de – Broglie wavelength of an electron is 600 nm. The velocity of the electron having the mass 9.1 X 10-31 Kg is
    • a)
      0.0012 x 10+4 m/s
    • b)
      0.0012 x 10+3 m/s
    • c)
      0.0012 x 10+6 m/s
    • d)
      0.0012 x 10+2 m/s
    Correct answer is option 'C'. Can you explain this answer?

    Arjun Gupta answered
    1nm= 10^-9m.
    wavelength= 600nm= 600 ×10-9m
    wavelength= h/p.
    wavelength= h/mv
    v= h/ m wavelength
    v=6.625×10^-34/9.1×10^-31×600× 10-9.
    v= 6.625 × 10+4/9.1 ×6.
    v= 6.625× 10+4/9.1×6.
    v= 6.625 ×104/54.6.
    v= 0.12 × 104.
    v= 0.0012 × 10+6 .

    Which model describes that there is no change in the energy of electrons as long as they keep revolving in the same energy level and atoms remains stable?
    • a)
      Rutherford Model
    • b)
      Bohr’s Model
    • c)
      J.J Thomson Model
    • d)
      None of the above
    Correct answer is option 'B'. Can you explain this answer?

    Suresh Reddy answered
    Bohr Model of atom:
    • An atom is made up of three particles: Electrons, neutrons and protons.
    • The protons and neutrons are located in a small nucleus at the centre of the atom.
    • The electrons revolve rapidly around the nucleus at the centre of the atom.
    • There is a limit to the number of electrons that each energy level can hold.
    • Each energy level is associated with a fixed amount of energy.
    • There is no change in the energy of electrons as long as they keep revolving in the same energy level.
    Bohr explained the stability through the concept of revolution of electrons in different energy levels.
    The change in the energy of an electron occurs when it jumps from lower to higher energy levels. When it gains energy, it excites from lower to higher and vice versa.
    Thus energy is not lost and the atom remains stable.

    The nature of positive rays depends on?
    • a)
        The nature of discharge tube.
    • b)
        The nature of residual gas
    • c)
        All of above.
    • d)
        The nature of electrode
    Correct answer is option 'B'. Can you explain this answer?

    The positive charges in these rays, other than negative cathode rays (which are electrons), depend on the gas that is used because they are cations - atoms with mostly one electron missing and thus one positive charge. So, if you accelerate, argon cations and protons over the same electric potential, the particles in the rays will have the same kinetic energy, but the argon ions will be much slower, as they are much heavier than the protons.

    Uncertainty in the position of an electron (mass 9.1 x 10-31 kg) moving with a velocity of 300 ms-1, accurate upto 0.001% will be:
    • a)
      1.92 x 10-2 m
    • b)
      3.84 x 10-2 m
    • c)
      19.2 x 10-2 m 
    • d)
      5.76 x 10-2 m
    Correct answer is option 'C'. Can you explain this answer?

    Lavanya Menon answered
    Change in position (X),
    P= momentum,
    P=mv.
    X ×P = h/4π.
    X× m v = h/4π.
    X= h/4πmv.
    X=6.625×10-34/4 ×3.14×9.1×10^-31×300.
    X=6.625×10-5/342.8.
    X=0.0192×10^-5.
    X= 19.2× 10-7.
    in question it is given to take accurate up to 0.001%.= 1×10-3/100=1 ×10-5.
    X= 19.2 ×10-7/10-5.
    X=19.2 × 10-2.

    The number of radial nodes for 3p orbital is __________.
    • a)
      3
    • b)
      4
    • c)
      2
    • d)
      1
    Correct answer is option 'D'. Can you explain this answer?

    Swara Saha answered
    Number of radial nodes = n-1 – 1
    For 3p orbital, n = 3 – 1 – 1 = 1
    Number of radial nodes = 3 – 1 – 1 = 1. 

    In the relationship ∆x. ∆p =   , ∆p is:
    • a)
      Certainty in momentum
    • b)
      Certainty in position
    • c)
      Uncertainty in momentum
    • d)
      Uncertainty in position
    Correct answer is option 'C'. Can you explain this answer?

    Hansa Sharma answered
    The uncertainty principle is alternatively expressed in terms of a particle’s momentum and position. The momentum of a particle is equal to the product of its mass times its velocity. Thus, the product of the uncertainties in the momentum and the position of a particle equals h/(4π) 

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