Rutherford's alpha-particle (α) scattering experiment was responsible for the discovery of which one of the following ?
- A.Electron
- B.Proton
- C.Atomic Nucleus
- D.Neutron
Correct answer
Explanation
The correct answer is C, Atomic Nucleus. Rutherford's gold foil experiment of 1911 showed that an atom's positive charge and almost all its mass sit in a tiny central nucleus.
Alpha particles were fired at a very thin gold foil. Most passed straight through, showing that the atom is mostly empty space; a few were deflected, and about one in twenty thousand bounced almost straight back. Rutherford reasoned that only a small, dense, positively charged centre could turn them back so sharply. This replaced Thomson's plum pudding model with the nuclear model, in which electrons move around the nucleus.
A is wrong because the electron was discovered by J. J. Thomson in 1897 using cathode rays. B is wrong because the proton was identified later from experiments on positive rays and nuclear reactions, not by the scattering experiment. D is wrong because the neutron was discovered by James Chadwick in 1932.
Exam tip: electron, Thomson (1897); nucleus, Rutherford (1911); neutron, Chadwick (1932).
Practice Questions
View allWho among the following built a model steam engine in 1698 called "Miner's Friend" to drain mines ?
- A.Thomas Savery
- B.Thomas Newcomen
- C.James Watt
- D.Richard Arkwright
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The English engineer Thomas Savery patented a steam pump in 1698 and called it the Miner's Friend, as it was meant to pump water out of flooded mines.
Read the full explanation →A metallic wire having resistance of 20 Ω is cut into two equal parts in length. These parts are then connected in parallel. The resistance of this parallel combination is equal to
- A.20 Ω
- B.10 Ω
- C.5 Ω
- D.15 Ω
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Each half of the wire has a resistance of 10 Ω, and two 10 Ω resistors in parallel give 5 Ω. The resistance of a wire is R = ρL/A, so it is directly proportional to its length when the material and thickness stay the same.
Read the full explanation →Myopia is a defect in human vision where an image of a
- A.nearby object is focused beyond the retina.
- B.nearby object is focused before the retina.
- C.distant object is focused before the retina.
- D.distant object is focused beyond the retina.
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In myopia, or short-sightedness, a person sees near objects clearly but distant objects look blurred because their image forms in front of the retina.
Read the full explanation →A homogeneous mixture contains two liquids. How are they separated ?
- A.By filtration
- B.By evaporation
- C.By distillation
- D.By condensation
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Two miscible liquids that form a homogeneous mixture are separated by distillation, which uses the difference in their boiling points.
Read the full explanation →Cartilage is NOT found in
- A.larynx
- B.nose
- C.ear
- D.urinary bladder
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The urinary bladder is a hollow muscular sac made of smooth muscle and a stretchable lining; it has no cartilage.
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