STRUCTURE OF ATOM(LEVEL 2)

• 1.

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

  by emission of electromagnetic radiation
  b 

  by absorption of any electromagnetic radiation
  c 

  by absorption of electromagnetic radiation of particular frequency
  d 

  without emission or absorption of electromagnetic radiation
  Difficulty Meter: 

  Very Hard (About 20% - 40% of users made it right)
  Explanation:

  Since the energy difference between two consecutive Bohr orbits is quantized and the energy of higher orbit is more than that of lower orbit, so an electron from one Bohr stationary orbit can go to next higher orbit by absorption of electromagnetic radiation of particular wavelength or frequency.
  Subject: 

  Chemistry
  Correct Answer: c

  Comment · 0 · 
• 2.

  In which pair of experimental observations and phenomenon does the experimental observation correctly accounts for the phenomenon?

  Experimental observation                           Phenomenon
  a 

  X-ray spectra                                   Charge on the nucleus
  b 

  a-particle scattering                   Quantized electron orbit
  c 

  Emission spectra                       The quantization of energy
  d 

  The photoelectric effect                 The nuclear atom
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  Emission spectra of different λ accounts for quantization of energy.
  Subject: 

  Chemistry
  Correct Answer: c

  Comment · 0 · 
• 3.

  If S₁ be the specific charge (e/m) of cathode rays and S₂ be that of positive rays than which is true?
  a 

  S₁ = S₂
  b 

  S₁ < S₂
  c 

  S₁ > S₂
  d 

  Either of these
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  Mass of positively charged ions in positive rays is more than mass of electrons.
  Subject: 

  Chemistry
  Correct Answer: c

  Comment · 0 · 
• 4.

  If E₁, E₂ and E₃ represent respectively the kinetic energies of an electron, an α particle and a proton each having same de-Broglie wavelength then:
  a 

  E₁ > E₃ > E₂
  b 

  E₂ > E₃ > E₁
  c 

  E₁ > E₂ > E₃
  d 

  E₁ = E₂ = E₃
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  $KE=\left(1/2\right)m{u}^2$

  and  $\lambda =\frac{h}{mu}$

  $\therefore$ $KE=\frac{1}{2}m\frac{h^2}{m^2{\lambda }^2}=\frac{h^2}{2m{\lambda }^2}$
  Subject: 

  Chemistry
  Correct Answer: a

  Comment · 0 · 
• 5.

  The de-Broglie wavelength of an electron in the ground state of hydrogen atom is : [K.E. = 13.6 eV; 1eV = 1.602x10^-19 J]
  a 

  33.28 nm
  b 

  3.328 nm
  c 

  0.3328 nm
  d 

  0.0332 nm
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  For electron in the ground state,

  
  Subject: 

  Chemistry
  Correct Answer: c

  Comment · 0 · 
• 6.

  The energy required to break one mole of Cl – Cl bonds in Cl₂ is 242 kJ mol^–1. The longest wavelength of light capable of breaking a single Cl – Cl bond is (c = 3 × 10⁸ ms^–1 and N_A= 6.02 × 10²³ mol^–1)
  a 

  594 nm
  b 

  640 nm
  c 

  700 nm
  d 

  494 nm
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  Energy required to break one mole of Cl – Cl bonds in Cl₂

  
  Subject: 

  Chemistry
  Correct Answer: d

  Comment · 0 · 
• 7.

  The orbital angular momentum for an electron revolving in an orbit is given by  This momentum for an s-electron will be given by
  a 

  zero
  b 

  
  c 

  
  d 

  
  Difficulty Meter: 

  Very Hard (About 20% - 40% of users made it right)
  Explanation:

  
  Subject: 

  Chemistry
  Correct Answer: a

  Comment · 0 · 
• 8.

  If  and  be the threshold wavelength and the wavelength of incident light, the velocity of photo-electrons ejected from the metal surface is:
  a 

  
  b 

  
  c 

  
  d 

  
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  As per Einstein’s equation of photoelectric effect hv = hv 0 + K.E.

  

  
  Subject: 

  Chemistry
  Correct Answer: c

  Comment · 0 · 
• 9.

  The energy of the electron in Be³⁺ ion depends on
  a 

  the principal quantum number only
  b 

  the principal and azimuthal quantum numbers only
  c 

  the principal, azimuthal and magnetic quantum numbers only
  d 

  the principal, azimuthal, magnetic and spin quantum numbers
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  Be³⁺ is hydrogenic ion, i.e. consists of one extra-nuclear electron.
  Subject: 

  Chemistry
  Correct Answer: a

  Comment · 0 · 
• 10.

  The given diagram indicates the energy levels of certain atoms. When the system moves from 2E level to E a photon of wave length  is emitted. The wave-length of photon produced during its transition from level to E is
  
  a 

  
  b 

  
  c 

  
  d 

  
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  From the given data, when the system moves from 2E level to E level, we have

  
  When the system moves from level to E level,
  we have
  
  Subject: 

  Chemistry
  Correct Answer: d

  Comment · 0 · 
• 11.

  Let m_p be the mass of a proton, m_n that of a neutron, M₁ that of a  Ne nucleus and M₂ that of a Ca nucleus. Then
  a 

  M₂ = 2M₁
  b 

  M₁ < 10(m_p + m_n)
  c 

  M₂ > 2M₁
  d 

  M₁ = M₂
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  
  Subject: 

  Chemistry
  Correct Answer: a

  Comment · 0 · 
• 12.

  If the shortest wavelength of the spectral line of H-atom in the Lyman series is x, then the longest wavelength of the line in Balmer series of Li²⁺ is
  a 

  9x
  b 

  
  c 

  
  d 

  
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  

  

  
  Subject: 

  Chemistry
  Correct Answer: d

  Comment · 0 · 
• 13.

  In a multi-electron atom, which of the following orbitals described by the three quantum members will have the same energy in the absence of magnetic and electric fields?
  (A) n = 1, l = 0, m = 0           (B) n = 2, l = 0, m = 0
  (C) n = 2, l = 1, m = 1          (D) n = 3, l = 2, m = 1
  (E) n = 3, l = 2, m = 0
  a 

  (D) and (E)
  b 

  (C) and (D)
  c 

  (B) and (C)
  d 

  (A) and (B)
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  The energy of an orbital is given by (n + ) in (D) and (E).(n + ) value is (3 + 2) = 5, hence they will have same energy, since there n values are also same.
  Subject: 

  Chemistry
  Correct Answer: a

  Comment · 0 · 
• 14.

  In a measurement of quantum efficiency of photosynthesis in green plants, it was found that 10 quanta of red light of wavelength 6850 Å were needed to release one molecule of O₂ . The average energy storage in this process is 112 kcal/mol O₂ evolved. What is the energy conversion efficiency in this experiment?
  Given : 1 cal = 4.18 J; N_A = 6 × 10²³ ; h = 6.63 × 10^–34 J.s
  a 

  23.5
  b 

  26.9
  c 

  66.34
  d 

  73.1
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  
  Energy stored for process
  
  Subject: 

  Chemistry
  Correct Answer: b

  Comment · 0 · 
• 15.

  The five d-orbitals are designated as d_xy , d_yz , d_xz , d_{x² - y²} and d_z² . Choose the correct statement.
  a 

  The shapes of the first three orbitals are similar but that of the fourth and fifth orbitals are different
  b 

  The shapes of all five d-orbitals are similar
  c 

  The shapes of the first four orbitals are similar but that of the fifth orbital is different
  d 

  The shapes of all five d-orbitals are different
  Difficulty Meter: 

  Intense (Only less than 20% of users made it right)
  Explanation:

  First four orbitals contain four lobes, while fifth orbital consists of only two lobes. The lobes of d_xy orbital lie between x and y axis. Similarly in the case of d_yz and d_zx. their lobes lie between yz and zx axis respectively. Four lobes of d_x²-y² orbital are lying along x and y axis while two lobes of  orbital are lying along z-axis.
  Subject: 

  Chemistry
  Correct Answer: c