Which one of the following findings is NOT observed in Rutherford's Nuclear Model of Atom?
- A.There is a neutral centre in an atom called nucleus
- B.Nearly all the mass of an atom resides in the nucleus
- C.The electrons revolve around the nucleus in a circular path
- D.The size of a nucleus is very small as compared to the size of atom
Correct answer
Explanation
The correct answer is A, There is a neutral centre in an atom called nucleus. Rutherford found the nucleus to be positively charged, not neutral.
In his gold foil experiment of 1911, Rutherford fired alpha particles at a very thin sheet of gold. Most passed straight through, showing that an atom is mostly empty space. A few were deflected sharply and about one in twenty thousand bounced back, which could happen only if they met a tiny, heavy, positively charged centre that repelled them. From this he proposed that the positive charge and almost all the mass sit in the nucleus, with electrons moving around it in circular paths.
B is part of the model: almost the whole mass of the atom is in the nucleus.
C is part of the model: electrons revolve round the nucleus in circular orbits, much like planets round the Sun.
D is part of the model: the nucleus is about 105 times smaller than the atom.
Exam tip: Rutherford, gold foil, positive and tiny nucleus (1911); his model could not explain why the atom is stable, which Bohr addressed.
Practice Questions
View allThe principle involved in paper chromatography is
- A.Absorption
- B.Partition
- C.Solubility
- D.Volatility
Show answer
Paper chromatography separates substances because each one divides, or partitions, itself differently between two liquid phases. In paper chromatography the stationary phase is the water held in the cellulose fibres of the paper, and the mobile phase is the solvent that rises up the paper by capillary action.
Read the full explanation →Which one of the following phenomena CANNOT be exhibited by sound waves ?
- A.Reflection
- B.Refraction
- C.Interference
- D.Polarisation
Show answer
Sound in air is a longitudinal wave, and only transverse waves can be polarised. Polarisation means restricting the vibrations of a wave to a single plane.
Read the full explanation →Which one of the following is NOT a luminous object ?
- A.Sun
- B.Electric lamp
- C.Candle
- D.Moon
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The Moon gives out no light of its own; it only reflects sunlight, so it is a non-luminous object. A luminous object produces and emits its own light, while a non-luminous object is seen only because it reflects light falling on it.
Read the full explanation →In experiment #1, a bar magnet is moved towards a conducting wire loop axially, with the magnet's north pole facing the loop. In experiment #2, the same process as in experiment #1 is repeated except that the south pole of the magnet faces the loop. Which one of the following statements is true in this context?
- A.The direction of current in the loop will be of opposite nature in both the experiments.
- B.The direction of current in the loop will be the same in both the experiments.
- C.No current will flow in either of the two experiments.
- D.More current will flow in the loop in experiment #1.
Show answer
Reversing the pole that approaches the loop reverses the change in magnetic flux, so the induced current reverses too. When a magnet moves towards a closed loop, the magnetic flux through the loop changes and an electric current is induced (Faraday's law of electromagnetic induction).
Read the full explanation →Which one of the following statements about classification of plants is correct?
- A.Thallophytes have well differentiated body design
- B.Funaria is a fungus
- C.All Pteridophytes are Phanerogams
- D.Vascular system is not found among Bryophytes
Show answer
Mosses and liverworts have no xylem or phloem, so water moves through them cell to cell. Bryophytes, such as Funaria (a moss) and Marchantia (a liverwort), are called the amphibians of the plant kingdom because they live on land but need water for fertilisation.
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