Elementary Ideas About The Structure of Atom, Atomic Equivalent and Molecular Weights, Valency NDA Questions

NDA Chemistry

Elementary Ideas About The Structure of Atom, Atomic Equivalent and Molecular Weights, Valency MCQ Questions


13.
What were the THREE key observations in Rutherford's alpha-particle scattering experiment?
A.
(1) Most alpha particles passed straight through (2) Some were deflected by small angles (3) One in every 12,000 particles bounced back
B.
(1) All particles bounced back (2) No particles passed through (3) All particles deflected equally
C.
(1) Particles split into protons and neutrons (2) Gold foil dissolved (3) Yellow light was emitted
D.
(1) Most particles deflected (2) Half bounced back (3) One particle passed through for every 100
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ANSWER :
A. (1) Most alpha particles passed straight through (2) Some were deflected by small angles (3) One in every 12,000 particles bounced back
14.
What conclusion did Rutherford draw about the NUCLEUS from his alpha-particle scattering experiment?
A.
The nucleus occupies most of the space inside the atom
B.
The atom has a tiny, dense, positively charged nucleus that contains all the positive charge and most of the mass of the atom
C.
The atom has an evenly distributed positive charge throughout its volume
D.
The nucleus is negatively charged and surrounded by positive electrons
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ANSWER :
B. The atom has a tiny, dense, positively charged nucleus that contains all the positive charge and most of the mass of the atom
15.
What are the LIMITATIONS of Rutherford's model of the atom?
A.
It assumed too many electrons in each shell which was later corrected
B.
It failed to include protons but successfully described neutrons
C.
It could not explain the stability of the atom — electrons revolving in circular orbits would continuously radiate energy, slow down, spiral inward and collapse into the nucleus
D.
It correctly explained atomic spectra but failed to explain atomic mass
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ANSWER :
C. It could not explain the stability of the atom — electrons revolving in circular orbits would continuously radiate energy, slow down, spiral inward and collapse into the nucleus
16.
What did Rutherford propose about the position of electrons in his model?
A.
Electrons are located only in the outermost regions of the atom
B.
Electrons are stationary around the nucleus
C.
Electrons are embedded in the nucleus
D.
Electrons revolve around the nucleus in circular orbits at high speed, and the electrostatic attraction of the nucleus balances the centrifugal force
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ANSWER :
D. Electrons revolve around the nucleus in circular orbits at high speed, and the electrostatic attraction of the nucleus balances the centrifugal force
17.
According to Rutherford's model, most of the atom is:
A.
Empty space (the electrons orbit at relatively large distances from the nucleus)
B.
Filled with a uniform distribution of positive charge
C.
Filled with electrons rotating in closely packed shells
D.
Filled with the dense nucleus
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ANSWER :
A. Empty space (the electrons orbit at relatively large distances from the nucleus)
18.
Bohr's model of the atom was proposed in which year and corrected which limitation of Rutherford's model?
A.
1920; Bohr resolved the mass-charge discrepancy in Rutherford's model
B.
1932; Bohr corrected the nuclear model by adding neutrons
C.
1897; Bohr corrected Thomson's model by proposing electrons orbit outside the positive sphere
D.
1913; Bohr resolved the stability problem by proposing that electrons revolve in fixed orbits of definite energy (stationary states) without radiating energy
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ANSWER :
D. 1913; Bohr resolved the stability problem by proposing that electrons revolve in fixed orbits of definite energy (stationary states) without radiating energy