Fundamentals of Atomic Structure and Cathode Rays

Test your knowledge on the basic building blocks of atoms and the discovery of the electron. This quiz covers fundamental particles, atomic models, and J.J. Thomson's cathode ray experiment.

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1. According to the text, who is credited with coining the term 'atom'?

J.J. Thomson Dr. A.O. Rajee John Dalton Rutherford

Explanation: The text explicitly states: 'John Dalton coined the term atom.'

2. The document states that an atom as a whole is electrically neutral because the number of protons is equal to the number of what?

neutrons electrons isotopes isobars

Explanation: The text says, '...the atom as the whole is electrically neutral as number of protons in it is equal to number of electrons.'

3. What conditions did J.J. Thomson use in the discharge tube to observe invisible radiations?

High voltage and high pressure Low voltage and very low pressure High voltage and very low pressure Low voltage and high pressure

Explanation: The text mentions, '...when a high voltage is applied between the electrodes fitted in discharge tube, at a very low pressure, some invisible radiations are emitted...'

4. In the discharge tube experiment, what visible phenomenon indicates the presence of cathode rays?

The gas in the tube turns red The tube becomes very hot A faint green glow appears on the tube wall Sparks are seen between the electrodes

Explanation: The diagram labels a 'Faint green glow' and the text states that the 'wall of the discharge tube near cathode starts glowing.' The glow is the visible effect.

5. Why does no electric current flow through the discharge tube when the gas pressure is at 1 atm?

The voltage is too low at that pressure The gases are poor conductors of electricity The electrodes are too far apart The glass tube insulates the current

Explanation: The text directly states, '...when the gas pressure in the tube is 1 atm, no electric current flows through the tube. This is because the gases are poor conductor of electricity.'

6. Based on the diagram, in which direction do the cathode rays travel?

From the positive anode to the negative cathode From the negative cathode to the positive anode From the vacuum pump into the tube From the center of the tube outwards

Explanation: The diagram shows the cathode connected to the negative terminal and the anode to the positive terminal, with dashed lines labeled 'Cathode rays' moving from the cathode toward the anode.

7. What is the primary origin of cathode rays, as described in the text?

Particles originating from the vacuum pump High-speed electrons emitted from the cathode Light produced by the high voltage Ionized gas molecules moving randomly

Explanation: The section 'Origin of Cathode rays' specifies they are caused by 'high-speed electrons emitted first from the cathode.'

8. The introductory paragraph describes the 'solar system' model of the atom as:

The most accurate modern theory Completely useless in all circumstances A model that may be useful but is ultimately an oversimplification A theory developed by J.J. Thomson

Explanation: The text says, 'In some circumstances, this "solar system" model of the atom may be useful, but you should know that the electron is much more unusual than that model suggests.'

9. According to the introduction, what is a major reason that an accurate verbal description of the electron is challenging?

Its extremely fast speed Its unpredictable color changes Its large and variable size The mathematical complexity involved

Explanation: The text states, 'The mathematical complexity alone makes an accurate verbal portrayal of the electron challenging...'

10. Which of the following is NOT listed as an 'AIM' of the lesson?

To introduce Fundamental particles To introduce Thomson's and Rutherford Atomic model To define the structure of the neutron To introduce terms like atomic number, mass number and isotopes

Explanation: The 'AIM' section lists introducing fundamental particles, Thomson's/Rutherford's model, and terms like atomic number. It does not mention defining the structure of the neutron specifically.

11. According to the text, which of the following is NOT a property of cathode rays?

They travel in straight lines with high speed. They are made up of material particles. They produce a cooling effect. They cause ionization of the gas through which they pass.

Explanation: Point (iv) under 'Properties of Cathode rays' explicitly states that they produce a heating effect, not a cooling effect.

12. What are the negatively charged material particles that constitute cathode rays called?

Protons Electrons Anode rays Canal rays

Explanation: The text states in point (iii) under 'Properties of Cathode rays' that 'the negatively charged material particles constituting the cathode rays are called electrons.'

13. Who is credited in the text with first discovering the presence of positive rays (anode rays)?

Ernest Rutherford Goldstein J.J. Thomson Dr. A.O. Rajee

Explanation: The section 'Discovery of proton - study of Anode rays' begins with the sentence: 'Goldstein discovered the presence of positive rays.'

14. In the experiment for producing anode rays, what was a crucial feature of the cathode used?

It was perforated. It was positively charged. It was coated with zinc sulphide. It was heated to a very high temperature.

Explanation: The text and the diagram both indicate that a 'perforated cathode' was used, which allowed the anode rays to pass through it.

15. How are anode rays (or positive rays) generated in the discharge tube?

They are emitted directly from the anode. Gas atoms in the tube lose electrons to become positively charged ions. Electrons are converted into positive particles. They are created when cathode rays collide with the anode.

Explanation: Under 'Origin of anode or positive rays', the text explains that 'atoms of gas lose negatively charged electrons. These atoms, thus, acquire a positive charge.'

16. How does the speed of anode rays compare to that of cathode rays?

Their speeds are identical. Anode rays are much faster. Anode rays are much slower. The text does not compare their speeds.

Explanation: The first point under 'Properties of Anode rays' states, 'However, their speed is much less than that of the cathode rays.'

17. What is produced when cathode rays strike the surface of hard metals like tungsten?

Green fluorescence Protons X-rays Anode rays

Explanation: Point (vi) of 'Properties of Cathode rays' states, 'They produce X-rays when they strike against the surface of hard metals like tungsten...'

18. The discovery of the proton is credited to Ernest Rutherford for proving that the nucleus of which atom is present in the nuclei of all other atoms?

Helium Oxygen Hydrogen Carbon

Explanation: The text credits Rutherford for proving 'that the nucleus of the hydrogen atom (i.e. a proton) is present in the nuclei of all other atoms in the year 1917.'

19. Does the nature of cathode rays depend on the type of gas used in the discharge tube or the material of the cathode?

Yes, it depends on both. It depends only on the gas. It depends only on the cathode material. No, it does not depend on either.

Explanation: Point (x) under 'Properties of Cathode rays' states that their nature 'does not depend upon the nature of the gas, taken in the discharge tube and the nature of cathode material.'

20. According to the text, what is another name for anode rays, aside from 'positive rays'?

Goldstein rays Rutherford rays Canal rays Alpha particles

Explanation: In the 'Discovery of proton' section, it is mentioned: 'These rays were called anode rays or canal rays or positive rays.'

21. According to the text, who discovered the neutron?

J.J. Thomson Ernest Rutherford Chadwick Millikan

Explanation: The text states under the 'Neutron' section, 'It was discovered by Chadwick...'. This is also confirmed in the summary table.

22. The charge of an electron was determined by Millikan using which experiment?

Gold foil experiment Oil drop experiment Cathode ray tube experiment Beryllium bombardment

Explanation: Under the 'Electron' section, the text explicitly says, 'Charge: It was determined by Millikan by oil drop experiment'.

23. Which of the following particles is described as the heaviest and least stable?

Electron Proton Neutron Alpha particle

Explanation: In the description of the Neutron, the last point states: 'Among all the elementary particles neutron is the heaviest and least stable.'

24. What is the mass of a proton as listed in the summary table?

9.109x10⁻³¹ kg 1.672x10⁻²⁷ kg 1.675x10⁻²⁷ kg 9.11x10⁻²⁸ g

Explanation: The summary table under the 'Proton' column and 'Mass' row lists the value as 1.672x10⁻²⁷ kg.

25. Based on the text, the nature of anode rays depends on what factor?

The type of cathode used The pressure inside the tube The gas taken in the discharge tube The voltage applied

Explanation: Point iv) under the initial list states: 'The nature of anode rays depends on the gas taken in the discharge tube.'

26. What is the charge on one mole of electrons, also known as?

1 coulomb 1 ampere 1 faraday 1 volt

Explanation: In the 'Electron' section, it is mentioned that the 'Charge on one mole of electron is 96500 coulombs or 1 faraday.'

27. According to the text, by how much is a neutron heavier than a proton?

1837 times 0.55% It is lighter 0.18%

Explanation: Under the 'Neutron' section, the text states its mass 'is heavier than proton by 0.18%.'

28. Where are electrons located within an atom, according to the summary table?

In the nucleus Orbiting the protons Outside the nucleus Both inside and outside the nucleus

Explanation: The last row of the summary table, 'Location', specifies 'Outside the nucleus' for the electron.

29. What is the specific charge (e/m ratio) of a proton mentioned in the document?

1.76x10⁸ coulomb/gm 9.58x10⁴ coulomb/gm 1.602x10⁻¹⁹ coulombs Zero

Explanation: Under section '2. Proton', the specific charge is listed as '9.58x10⁴ coulomb/gm'.

30. The discovery of the neutron involved bombarding a Beryllium (Be) atom with what type of particle?

Electrons Protons Alpha particles (He) Gamma rays

Explanation: The text describes the discovery of the neutron as 'by bombarding Be atom with high speed α-particles.' The provided nuclear equation ⁴Be⁹ + ₂He⁴ → ₆C¹² + ₀n¹ confirms the alpha particle (₂He⁴).

31. According to Thomson's Atomic Model as described in the text, what is the fundamental structure of an atom?

A) A dense, positively charged nucleus with electrons orbiting it. B) A sphere of positive charge with electrons embedded in it to ensure neutrality. C) A solid, indivisible particle without any internal structure. D) A collection of electrons held together by gravitational forces.

Explanation: The text states, 'According to Thomson, an atom is a sphere of positive charge having a number of embedded electrons in it and sufficient enough to neutralize the positive charge.'

32. Which analogy is used in the document to describe Thomson's Atomic Model?

A) A solar system B) An onion with layers C) A watermelon or plum pudding D) A billiard ball

Explanation: The text mentions, 'This model is compared with a water melon in which seeds are embedded or pudding in which raisins are embedded. Therefore, this model, sometime called watermelon model or raisin or plum pudding model.'

33. What was a major limitation of Thomson's model mentioned in the text?

A) It couldn't explain the existence of isotopes. B) It failed to explain the results of Rutherford's scattering experiment. C) It did not account for the mass of the atom. D) It contradicted the law of conservation of energy.

Explanation: Under the 'Limitation' section, the text explicitly states: 'This model failed explain the results of scattering experiment of Rutherford and the stability of atom.'

34. In Rutherford's α-ray scattering experiment, what was the purpose of the zinc sulphide (ZnS) screen?

A) To generate the beam of alpha particles. B) To hold the thin gold foil in place. C) To deflect the alpha particles towards the target. D) To detect the alpha particles after they passed through the foil.

Explanation: The document states that the presence of α-particles was 'detected with the help of a circular zinc sulphide screen. The point at which an α-particle strikes this screen, a flash of light is given out.'

35. What was the primary observation made during Rutherford's gold foil experiment, as noted in the text?

A) All α-particles bounced directly back from the foil. B) Most of the α-particles passed through the foil without any deflection. C) All α-particles were deflected at a 90-degree angle. D) The α-particles were absorbed by the gold foil and disappeared.

Explanation: The first point under 'Observations and Conclusions' clearly states, 'Most of the α-particles passed through the gold foil without any deflection from their original path.'

36. What conclusion did Rutherford draw from the observation that most α-particles passed straight through the gold foil?

A) The atom is uniformly dense. B) The atom is mostly empty space. C) The positive charge is spread evenly throughout the atom. D) The gold foil was not thin enough.

Explanation: The text explains the conclusion from this observation: 'Bcz [because] atom has largely empty space as most of the α-particles passed through the foil undeflected.'

37. What type of particles were used to bombard the thin metal foils in Rutherford's experiment?

A) Electrons B) Protons C) Neutrons D) Alpha (α) particles

Explanation: The section on Rutherford's Atomic Model describes it as an 'α-ray scattering experiment' and mentions bombarding foils 'with a beam of fast moving radioactive particles'. The diagram further clarifies this, labeling the 'Beam of α-particles'.

38. Based on the diagram of Rutherford's experimental setup, where did the beam of α-particles originate?

A) From the gold foil itself B) From the ZnS screen C) From a radioactive source placed in a lead block D) From an external particle accelerator

Explanation: The diagram clearly shows a box labeled 'radioactive source' from which the beam emerges. The text also mentions the particles 'originated from a lead block'.

39. What does the diagram illustrating the 'Observations and Conclusions' of Rutherford's experiment show about the path of α-particles near the nucleus?

A) All particles pass through the nucleus. B) Particles passing far from the nucleus are undeflected, while those closer are deflected. C) All particles are deflected by the same amount. D) The nucleus attracts the α-particles, causing them to curve inwards.

Explanation: The diagram shows multiple parallel α-particle paths. The ones far from the central positive nucleus continue straight, while the one passing closer is shown being deflected away from it.

40. According to the text, why are a few alpha particles deflected at large angles in Rutherford's experiment?

They collide with the electrons. There is a heavy positive charge at the center of the atom. The atom is mostly hollow with a lot of empty space. The particles are attracted to the nucleus.

Explanation: The text states, 'Bcz there is heavy positive charge at the center of the atom which causes repulsions', leading to the deflection of the positively charged alpha particles.

41. Based on Rutherford's model as described, what is responsible for the majority of an atom's mass?

The electrons revolving in orbits. The extra nuclear part. The nucleus. The empty space within the atom.

Explanation: Point (iii) under the initial observations and point 6 under 'According to Rutherford' both state that the nucleus is responsible for the mass of the atom.

42. Why is the atom considered electrically neutral according to Rutherford's model?

The nucleus has no charge. The number of electrons equals the number of units of positive charge in the nucleus. The electrons are held by electrostatic forces. The atom is spherical and mostly hollow.

Explanation: Point 4 explicitly states, 'The number of extra nuclear electrons is equal to the number of units of positive charge in the nucleus. Therefore the atom is electrically neutral.'

43. Rutherford's atomic model is also known as the 'planetary model' because it resembles what system?

A galaxy The solar system A star cluster The Earth-Moon system

Explanation: Point 5 mentions, 'Rutherford's model has resemblances with solar system. Hence it's also known as planetary model of the atom.'

44. What is the primary drawback of Rutherford's model, based on Maxwell's electromagnetic theory?

The nucleus is too small and dense. The atom cannot be hollow. An accelerating charged particle, like an orbiting electron, should continuously emit radiation and lose energy. It fails to explain the positive charge of the nucleus.

Explanation: The first drawback listed states that according to Maxwell's theory, 'when a charged particle moves under the influence of attractive force it loses energy continuously in the form of electromagnetic radiation'.

45. What is the predicted outcome if an electron continuously loses energy as described in the drawbacks of Rutherford's model?

The electron will be ejected from the atom. The electron will follow a spiral path and fall into the nucleus. The atom will gain a net positive charge. The electron's speed will increase.

Explanation: The text explains, 'the electron should lose energy at every turn and move closer and closer to the nucleus following a spiral path. The ultimate result is that it will fall into the nucleus...'

46. Ultimately, the first drawback implies that Rutherford's model cannot explain the ________ of the atom.

mass volume stability neutrality

Explanation: The conclusion of the first drawback is, '...thereby making the atom unstable. i.e., Rutherford's model cannot explain the stability of the atom.'

47. If electrons were to lose energy continuously as Rutherford's model suggests, what type of spectrum would be expected?

A continuous spectrum A spectrum of well-defined lines An absorption spectrum No spectrum at all

Explanation: The second drawback states, 'If the electrons lose energy continuously, the spectrum is expected to be continuous...'

48. In contrast to the prediction from Rutherford's model, what does the text state about the actual observed spectrum of an atom?

It is a continuous band of colors. It is invisible to the naked eye. It consists of well-defined lines of definite frequencies. It is identical for all elements.

Explanation: The text clarifies, '...but the actual observed spectrum consists of well-defined lines of definite frequencies.'

49. According to Rutherford's model, what part of the atom is responsible for its volume?

The nucleus The protons The neutrons The extra nuclear part where electrons are present

Explanation: Point 6 states, 'There is an empty space around the nucleus called extra nuclear part... the extra nuclear part is responsible for its volume.'