Atoms Objective Questions
- The first model of atom in 1898 was proposed by
(a) Ernst Rutherford
(b) Albert Einstein
(c) J.J. Thomson
(d) Niels Bohr
Answer: (c) J.J. Thomson
- In Geiger-Marsden scattering experiment, the trajectory traced by an a-particle depends on
(a) number of collision
(b) number of scattered a-particles
(c) impact parameter
(d) none of these
Answer: (c) impact parameter
- In the Geiger-Marsden scattering experiment the number of scattered particles detected are maximum and minimum at the scattering angles respectively at
(a) 0° and 180°
(b) 180° and 0°
(c) 90° and 180°
(d) 45° and 90°
Answer: (a) 0° and 180°
- In the Geiger-Marsden scattering experiment, is case of head-on collision the impact parameter should be
(a) maximum
(b) minimum
(c) infinite
(d) zero
Answer: (a) maximum
- Rutherford’s experiments suggested that the size of the nucleus is about
(a) 10-14 m to 10-12 m
(b) 10-15 m to 10-13 m
(c) 10-15 m to 10-14 m
(d) 10-15 m to 10-12 m
Answer: (c) 10-15 m to 10-14 m
- Which of the following spectral series falls within the visible range of electromagnetic radiation?
(a) Lyman series
(b) Balmer series
(c) Paschen seriee
(d) Pfund series
Answer: (b) Balmer series
- The first spectral series was discovered by
(a) Balmer
(b) Lyman
(c) Paschen
(d) Pfund
Answer: (a) Balmer
- Which of the following postulates of the Bohr model led to the quantization of energy of the hydrogen atom?
(a) The electron goes around the nucleus in circular orbits.
(b) The angular momentum of the electron can only be an integral multiple of h/2π.
(c) The magnitude of the linear momentum of the electron is quantized.
(d) Quantization of energy is itself a postulate of the Bohr model.
Answer: (b) The angular momentum of the electron can only be an integral multiple of h/2π.
- The Bohr model of atoms
(a) assumes that the angular momentum of elec-trons is quantized.
(b) uses Einstein’s photoelectric equation.
(c) predicts continuous emission spectra for at-oms.
(d) predicts the same emission spectra for all types of atoms.
Answer: (a) assumes that the angular momentum of elec-trons is quantized.
- The Bohr model of atoms :
(A) assumes that the angular momentum of electrons is quantized
(B) uses Einstein’s photoelectric equation
(C) predicts continuous emission spectra for atoms
(D) predicts the same emission spectra for all types of atoms
Answer: (A) assumes that the angular momentum of electrons is quantized
- Who explained the splitting of special lines in magnetic field ?
(A) Zeeman
(B) Bohr
(C) Summerfield
(D) Einstein
Answer: (A) Zeeman
- The mass of a neutron is :
(A) 1.00866 u
(B) 1.0866 u
(C) 1.866 u
(D) 0.1866 u
Answer: (A) 1.00866 u
- Half-life of a substance depends on:
(A) pressure
(B) temperature
(C) density
(D) None of these
Answer: (D) None of these
- The concept of electron spin was introduced by :
(A) Becquerel
(B) Goudsmit
(C) Millikan
(D) Uhlenbeck and Goudsmith
Answer: (D) Uhlenbeck and Goudsmith
- β-decay produces :
(A) isobars
(B) isotopes
(C) isotones
(D) All the above
Answer: (A) isobars
- Transmutation of nuclei was discovered by :
(A) Rutherford
(B) Becquerel
(C) Pauli
(D) None of these
Answer: (A) Rutherford
- The energy equivalent to mass defect is called :
(A) binding energy
(B) internal energy
(C) external energy
(R) enthalpy
Answer: (A) binding energy
- The binding energy of He is about :
(A) 28.3 eV
(B) 28.3 Mev
(C) 28.3 J
(D) 2.83 Mev
Answer: (B) 28.3 Mev
- The binding energy of a deuteron is about :
(A) 2.22 MeV
(B) 2.22 J
(C) 2.22 eV
(D) None of these
Answer: (A) 2.22 MeV
- Who discovered the positron ?
(A) Chadwick
(B) Bohr
(C) Maxwell
(D) Anderson
Answer: (D) Anderson
- The mass of proton is about :
(A) 9.11 x 10-31 kg
(B) 9.11 x 10-30 kg .
(C) 1.66 x 10-27 kg
(D) 1 kg
Answer: (C) 1.66 x 10-27 kg
- Chadwick was awarded the Nobel Prize in Physics in 1935 for his discovery of :
(A) electron
(B) proton
(C) neutron
(D) None of these
Answer: (C) neutron
- The half life of a radioactive decay is n times its mean life, n is equal to :
(A) 0.6930
(B) 0.0693
(C) 1 / 0.6930
(D) 0.3070
Answer: (A) 0.6930
- Rutherford is the unit of:
(A) radioactivity
(B) energy
(C) photoelectric current
(D) magnetic field
Answer: (A) radioactivity
- The wavelength of Y -rays is of the order of:
(A) 10-8 m
(B) 10-5 me
(C) 10-11 m
(D) 10-22 m
Answer: (C) 10-11 m
- Which series of hydrogen spectrum does not lie in infrared region?
(A) Humphreys series
(B) Pfund series
(C) Bracket series
(D) Lyman series
Answer: (D) Lyman series
- The energy of electron in first Bohr orbit of hydrogen atom is -13.6 eV. What is energy of electron in its 2nd Both-orbit.
(A) – 3.4 eV
(B) – 6.8 eV
(C) – 27.2 eV,
(D) + 3.4 eV
Answer: (A) – 3.4 eV
- Full wave rectifier uses :
(A) two diodes
(B) three diodes
(C) four diodes
(D) five diodes
Answer: (A) two diodes
- The atomic number and mass number for a specimen are Z and A respectively. The number of neutrons in the atom will be :
(A) A
(B) Z
(C) A + Z
(D) A-Z
Answer: (D) A-Z
