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Indian Navy 10+2 B.Tech Cadet Class9 Atom Structure — practice questions

Explore 37 free Class9 Atom Structure questions in Indian Navy 10+2 B.Tech Cadet Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Class9 Atom Structure questions and exercises with answers

Showing questions 1–30 of 37.

The minimum energy required to remove an electron from the ground state of a hydrogen atom is:Read the answer and worked solution →de Broglie wavelength of an electron with momentum p:Read the answer and worked solution →In the photoelectric effect, the kinetic energy of the ejected electron depends onRead the answer and worked solution →The longest wavelength line in the Lyman series of hydrogen corresponds to the transitionRead the answer and worked solution →The Bohr radius for hydrogen ($n=1, Z=1$) is approximatelyRead the answer and worked solution →As per your syllabus, what is the molar mass of SODIUM CHLORIDE (NaCl)?Read the answer and worked solution →As per your syllabus, the radius of the first Bohr orbit of hydrogen (n = 1) — the Bohr radius a₀ — is approximately which value?Read the answer and worked solution →As per your syllabus, eqn 2.15, the radius of the n-th Bohr orbit for a hydrogen-like ion (one electron, atomic number Z) scales as which expression?Read the answer and worked solution →As per your syllabus, the magnetic quantum number m_l takes how many values for a given azimuthal quantum number l?Read the answer and worked solution →As per your syllabus, the electron-spin quantum number m_s — introduced by Uhlenbeck and Goudsmit (1925) — takes which values?Read the answer and worked solution →Hund's rule states that electrons in degenerate orbitals:Read the answer and worked solution →Order the atomic models as they were proposedRead the answer and worked solution →Match each scientist to their modelRead the answer and worked solution →Match each model to what it could NOT explainRead the answer and worked solution →True or false: Rutherford's modelRead the answer and worked solution →True or false: Bohr's modelRead the answer and worked solution →Complete the reason Bohr's model failsRead the answer and worked solution →Which model does this belong to?Read the answer and worked solution →Match each quantum number to what it is calledRead the answer and worked solution →True or false: the quantum mechanical modelRead the answer and worked solution →Order the structure: from atom down to electronRead the answer and worked solution →Complete the (n + l) ruleRead the answer and worked solution →True or false: orbital energiesRead the answer and worked solution →Match each rule to what it forbids or requiresRead the answer and worked solution →Tap every statement Hund's rule requiresRead the answer and worked solution →The fundamental particlesRead the answer and worked solution →Assertion and reasonRead the answer and worked solution →Two are true, one is notRead the answer and worked solution →Three of these are wrong. Find the one that holds.Read the answer and worked solution →Which principle is being described?Read the answer and worked solution →

Worked practice questions

The minimum energy required to remove an electron from the ground state of a hydrogen atom is:

  1. $3.4\,\text{eV}$
  2. $13.6\,\text{eV}$
  3. $27.2\,\text{eV}$
  4. $1.51\,\text{eV}$
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Correct answer: B. $13.6\,\text{eV}$

Ionisation energy is the energy required to take the electron from $n = 1$ to $n = \infty$. $E_\infty - E_1 = 0 - (-13.6) = 13.6\,\text{eV}$. The value $27.2\,\text{eV}$ is the magnitude of the potential energy in the ground state, not the ionisation energy.

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de Broglie wavelength of an electron with momentum p:

  1. λ = h / p
  2. λ = p / h
  3. λ = h × p
  4. λ = h c / p
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Correct answer: A. λ = h / p

de Broglie: λ = h/p. Every particle has wavelike properties with wavelength inversely proportional to momentum. For macroscopic objects (large p), λ is unmeasurably small. For electrons, λ is comparable to atomic dimensions.

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In the photoelectric effect, the kinetic energy of the ejected electron depends on

  1. the intensity of the incident light
  2. the frequency of the incident light
  3. the colour of the metal surface
  4. the temperature of the metal
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Correct answer: B. the frequency of the incident light

$KE_{max} = h\nu - \phi$ where $\phi$ is the work function. KE depends only on *frequency* intensity only changes the *number* of ejected electrons, not their energy. This is Einstein's resolution of the photoelectric puzzle.

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