NEET UG class9_atom_structure — practice questions
120 free MCQs with worked solutions. Tap any question for the answer + explanation, or practice them all in the app.
Practice NEET UG class9_atom_structure in the app →Rutherford's α-particle scattering experiment used a thin gold foil and showed that:In Rutherford's atomic model, electrons revolve around the nucleus due to:A key failure of Rutherford's classical model was that an accelerating electron should:In Bohr's model of the hydrogen atom, electrons can only occupy orbits in which the angular momentum is an intThe radius of the n-th Bohr orbit for hydrogen is proportional to:The Bohr radius a_0 is approximately:In Bohr's model, the energy of the n-th level of hydrogen is:The ground-state (n = 1) energy of the hydrogen atom is approximately:The energy of the first excited state (n = 2) of hydrogen is:The ionisation energy of hydrogen from its ground state is approximately:When a hydrogen atom makes a transition from n = 2 to n = 1, the energy of the emitted photon is approximatelyA photon emitted in a Bohr-model transition between levels n_i and n_f has frequency given by:The wave number $\bar{\nu}$ of electromagnetic radiation is defined asIn vacuum, the velocity of electromagnetic radiation isA photon has wavelength $400\,nm$. Its frequency is approximatelyThe wave number of a photon of frequency $6 \times 10^{14}\,Hz$ (in vacuum) isAccording to Planck's quantum theory, energy is emitted or absorbed in discrete packets calledThe energy of a photon of wavelength $\lambda$ is given byA photon of wavelength $300\,nm$ has approximately what energy in eV? (Use $hc = 1240\,eV\,nm$.)In the photoelectric effect, the kinetic energy of the ejected electron depends onThe threshold frequency $\nu_0$ for a metal is the minimum frequencyLight of frequency $\nu = 2\nu_0$ ejects photoelectrons from a metal with threshold frequency $\nu_0$. The maxIn a photoelectric experiment, doubling the *intensity* of incident light (frequency unchanged) willRutherford's $\alpha$-particle scattering experiment used a thin foil of which metal?In Rutherford's experiment, the observation that a few $\alpha$-particles bounced *back* impliedThe radius of a nucleus of mass number $A$ is approximately $R = R_0 A^{1/3}$ with $R_0 = 1.33 \times 10^{-15}Bohr's postulate quantises the angular momentum of an electron in a stationary orbit asFor a hydrogen-like atom of nuclear charge $Z$, the radius of the $n$th Bohr orbit scales asThe energy of the $n$th Bohr orbit of a hydrogen-like atom isThe ratio of the radii of the third Bohr orbit of $He^+$ and the first Bohr orbit of $H$ isThe velocity of the electron in the $n$th Bohr orbit of a hydrogen-like atom is proportional toThe energy required to remove the electron from the first excited state ($n=2$) of $He^+$ isWhich series of the hydrogen spectrum lies entirely in the *visible* region?Rydberg's formula for the wave number of a hydrogen spectral line isWhen an electron in a hydrogen atom returns to the ground state from $n = 5$, the maximum number of distinct sThe longest wavelength line in the Lyman series of hydrogen corresponds to the transitionA hydrogen atom in its ground state absorbs a photon and is excited to $n = 4$. The number of *possible* spectThe de Broglie wavelength of a particle of mass $m$ and momentum $p$ isThe de Broglie wavelength of an electron in the $n$th Bohr orbit, in terms of the orbit radius $r_n$, isAn electron is accelerated through a potential difference of $100\,V$. Its de Broglie wavelength is approximatHeisenberg's uncertainty principle relates the uncertainties in position and momentum asThe minimum uncertainty in the velocity of an electron whose position is known to within $\Delta x = 0.1\,nm$ The principal quantum number $n$ can take valuesFor principal quantum number $n$, the orbital quantum number $l$ takes valuesFor orbital quantum number $l$, the magnetic quantum number $m_l$ takes valuesHow many orbitals are present in the $n = 3$ shell?The maximum number of electrons in the subshell with $n = 4, l = 2$ isWhich set of quantum numbers $(n, l, m_l, m_s)$ is **NOT** allowed?Hund's rule applies during the filling ofThe Aufbau principle dictates that orbitals fill in order of increasingWhich of the following orbital shapes is dumbbell-shaped along an axis?How many *angular* nodes does a $3d$ orbital have?The number of *radial* nodes in a $4s$ orbital isThe ionisation energy of hydrogen in its ground state isFor $He^+$, the ionisation energy from its ground state isWhich transition in the hydrogen atom emits the largest amount of energy?Which of the following experimental phenomena could **NOT** be explained by classical EM wave theory?The Bohr model failed to explainIn the photoelectric effect, the *stopping potential* $V_0$ varies with the frequency of incident light asWhich of the following is **NOT** a possible set of quantum numbers for a 3d electron?The total number of electrons that can fit in the $M$ shell ($n=3$) isThe Bohr radius for hydrogen ($n=1, Z=1$) is approximatelyThe proton was discovered through experiments involvingThe neutron was discovered byIn Thomson's atomic model (plum-pudding), the atom isThe Bohr orbit velocity of the ground-state electron in hydrogen is aboutThe Rydberg constant for hydrogen, in SI units, isWhich statement is wrong about Bohr's theoryWhich of the following is incorrect?Find the formula of halide of a metal whose successive ionization energies are 10, 16, 25, 400, 500 eV mol$^{-The distance between 4th and 3rd Bohr orbits of $He^{+}$ is:Per NCERT Class 11 Chemistry, what is the ATOMIC MASS UNIT (u) — used to express atomic masses?Per NCERT, what is the AVERAGE ATOMIC MASS of an element — and why is it used?Per NCERT Exercise 1.9, using ³⁵Cl (75.77%, mass 34.9689) and ³⁷Cl (24.23%, mass 36.9659), what is the AVERAGEPer NCERT, what is MOLECULAR MASS — and how is it calculated?Per NCERT, what is the MOLECULAR MASS of methane (CH₄) — using C = 12.011 u and H = 1.008 u?Per NCERT, what is the MOLECULAR MASS of glucose (C₆H₁₂O₆) — using C=12.01, H=1.008, O=16.00?Per NCERT, what is the molar mass of WATER (H₂O)?Per NCERT, what is the molar mass of SODIUM CHLORIDE (NaCl)?Per NCERT, for IONIC compounds like NaCl, why do we use the term 'FORMULA MASS' instead of 'molecular mass'?Per NCERT, MOLAR MASS of a substance is defined as which value?Per NCERT, since the mass of one ¹²C atom is 1.992648 × 10⁻²³ g and one mole of carbon weighs 12 g, the numberPer NCERT, the AVERAGE ATOMIC MASS of carbon is shown in the periodic table as approximately 12.011 u — even tPer NCERT, the charge-to-mass ratio e/m_e of the electron, measured by J.J. Thomson in 1897, is which value?Per NCERT, which experiment determined the charge on the electron as −1.602 × 10⁻¹⁹ C?Per NCERT, which of the following is the correct mass of the electron derived from Millikan's e and Thomson's Per NCERT, key observation from cathode-ray experiments was that the characteristics of cathode rays did NOT dPer NCERT, who discovered the NEUTRON, by what experiment, and in what year?Per NCERT Table 2.1, which fundamental particle has approximate mass 1.674927 × 10⁻²⁷ kg and zero charge?Per NCERT, the smallest and lightest positive ion (a proton) was obtained from which gas in modified cathode-rPer NCERT eqn 2.3 + 2.4, for a neutral atom what relations hold between atomic number Z, mass number A, and coPer NCERT Problem 2.1, in ⁸⁰₃₅Br how many neutrons, protons and electrons are present (assuming neutral atom)?Per NCERT, which pair of nuclides represents ISOBARS (same A, different Z)?Per NCERT, isotopes of hydrogen include protium (¹H), deuterium (²H), and tritium (³H). What distinguishes thePer NCERT Problem 2.2, a species with 18 electrons, 16 protons, and 16 neutrons has what symbol?Per NCERT, the Thomson model of the atom is best described by which informal name?Per NCERT §2.2.2, in Rutherford's α-scattering on a gold foil, approximately how many α-particles bounced backPer NCERT, what comparative analogy does the textbook use to convey the relative sizes of the atom vs nucleus?Per NCERT, what was the MAJOR DRAWBACK of the Rutherford nuclear model?Per Bohr postulate (eqn 2.11), the angular momentum of an electron in the n-th allowed orbit is quantised as wPer Bohr's model (eqn 2.13), the energy of the electron in the n-th stationary state of the hydrogen atom is wPer NCERT, the radius of the first Bohr orbit of hydrogen (n = 1) — the Bohr radius a₀ — is approximately whicPer NCERT Problem 2.11, what is the energy of the first orbit of He⁺ (Z = 2, n = 1)?Per NCERT eqn 2.15, the radius of the n-th Bohr orbit for a hydrogen-like ion (one electron, atomic number Z) Per NCERT Table 2.3, in the hydrogen-atom spectrum the BALMER series corresponds to transitions ending in n₁ =Per NCERT eqn 2.9, the Rydberg formula for all spectral lines in hydrogen uses a constant value of approximatePer NCERT §2.4.2 (limitations), Bohr's model FAILED to explain which set of phenomena?Per NCERT eqn 2.5, the relation between the frequency ν, wavelength λ, and the speed of light c in vacuum is wPer NCERT Problem 2.5, the WAVENUMBER ν̄ of EM radiation is defined as which quantity?Per NCERT eqn 2.6, Planck's quantum hypothesis (1900) states that the energy of a quantum of radiation is whicPer NCERT §photoelectric effect, which of the following classical predictions does the photoelectric effect VIPer NCERT eqn 2.7, Einstein's photoelectric equation gives the kinetic energy of an ejected electron as which Per NCERT Problem 2.6, what is the energy of one mole of photons of radiation of frequency 5 × 10¹⁴ Hz?Per NCERT Table 2.3, the LYMAN series (n₁ = 1) of hydrogen lines lies in which spectral region?Per NCERT eqn 2.22, the de Broglie wavelength λ of a particle of momentum p (or mass m, velocity v) is which ePer NCERT eqn 2.23, Heisenberg's uncertainty principle (1927) states which inequality between uncertainty in pPer NCERT §2.5.2 (significance), what is the key consequence of the uncertainty principle for the concept of aPer NCERT eqn 2.17, the energy gap ΔE between two stationary states n_i and n_f in hydrogen is which expressioPer NCERT Problem 2.16 (golf ball, mass 40 g, 2% speed uncertainty), why does the uncertainty principle place Per NCERT §2.6.1, the principal quantum number n takes which values, and what does it primarily determine?