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Atoms

Each subtopic includes About section, revision page link, 10 preview questions, and practice CTAs.

Alpha-particle Scattering Experiment

Subtopic

Alpha-particle Scattering Experiment under Atoms for Grade 12 CBSE.

About Topic & Revision

Preview questions (no answers)

  1. 1.

    What is the approximate size of the nucleus as estimated from the α\alpha-particle scattering experiment?

    A.

    10−1010^{-10} m

    B.

    10−1510^{-15} m

    C.

    10−810^{-8} m

    D.

    10−1210^{-12} m

  2. 2.

    Which of the following components was used to detect the scattered α\alpha-particles in Rutherford’s experiment?

    A.

    A Geiger-Muller counter

    B.

    A photographic plate

    C.

    A rotating Zinc Sulphide (ZnS) screen with a microscope

    D.

    A Wilson cloud chamber

  3. 3.

    Most of the α\alpha-particles in the Geiger-Marsden experiment passed through the gold foil undeflected. What did this observation signify?

    A.

    The nucleus is very heavy.

    B.

    The entire atom is a solid sphere of positive charge.

    C.

    Most of the space inside the atom is empty.

    D.

    α\alpha-particles are attracted by the electrons.

Download the worksheet for Atoms - Alpha-particle Scattering Experiment to practice offline. It includes additional chapter-level practice questions.

Bohr’s Model of Hydrogen Atom

Subtopic

Bohr’s Model of Hydrogen Atom under Atoms for Grade 12 CBSE.

About Topic & Revision

Preview questions (no answers)

  1. 1.

    Bohr's third postulate states that the frequency ν\nu of the photon emitted during a transition from a higher energy level EiE_i to a lower energy level EfE_f is:

    A.

    ν=h(Ei−Ef)\nu = h(E_i - E_f)

    B.

    ν=Ei−Efh\nu = \frac{E_i - E_f}{h}

    C.

    ν=Ei+Efh\nu = \frac{E_i + E_f}{h}

    D.

    ν=hEi−Ef\nu = \frac{h}{E_i - E_f}

  2. 2.

    The total energy of an electron in the ground state of a hydrogen atom is −13.6 eV-13.6\text{ eV}. What is the potential energy of the electron in this state?

    A.

    −13.6 eV-13.6\text{ eV}

    B.

    +13.6 eV+13.6\text{ eV}

    C.

    −27.2 eV-27.2\text{ eV}

    D.

    +27.2 eV+27.2\text{ eV}

  3. 3.

    In the Bohr model of the hydrogen atom, how does the radius of the nthn^{th} orbit (rnr_n) relate to the principal quantum number nn?

    A.

    rn∝nr_n \propto n

    B.

    rn∝1n2r_n \propto \frac{1}{n^2}

    C.

    rn∝n2r_n \propto n^2

    D.

    rn∝nr_n \propto \sqrt{n}

Download the worksheet for Atoms - Bohr’s Model of Hydrogen Atom to practice offline. It includes additional chapter-level practice questions.

Hydrogen Line Spectra

Subtopic

Hydrogen Line Spectra under Atoms for Grade 12 CBSE.

About Topic & Revision

Preview questions (no answers)

  1. 1.

    For the Paschen series in the hydrogen spectrum, the electron transitions from outer orbits always end at the orbit with principal quantum number (nn) equal to:

    A.

    1

    B.

    2

    C.

    3

    D.

    4

  2. 2.

    The value of the Rydberg constant (RR) for hydrogen is approximately:

    A.

    1.097×107 m−11.097 \times 10^7 \text{ m}^{-1}

    B.

    6.63×10−34 J s6.63 \times 10^{-34} \text{ J s}

    C.

    8.85×10−12 C2/(N m2)8.85 \times 10^{-12} \text{ C}^2/(\text{N m}^2)

    D.

    1.6×10−19 C1.6 \times 10^{-19} \text{ C}

  3. 3.

    According to the Bohr model, an emission line is observed in the hydrogen spectrum when an electron:

    A.

    Moves from a lower energy level to a higher energy level

    B.

    Jumps from a higher energy level to a lower energy level

    C.

    Is completely removed from the atom (ionization)

    D.

    Orbits in a stable circular path without losing energy

Download the worksheet for Atoms - Hydrogen Line Spectra to practice offline. It includes additional chapter-level practice questions.

Atoms - CBSE Class 12 Physics Notes & Revision | Krit.club