Physics Chapter on Cathode Rays and Atomic Theory

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Which property of cathode rays indicates they are composed of charged particles?

Their deflection towards positive plates in an electric field. (correct)
Their production of light when striking the glass.
Their independence from the gas in the discharge tube and cathode material.
Their ability to travel in straight lines.

If the gas in a discharge tube is changed from hydrogen to neon, what would be the expected alteration in the characteristics of cathode rays?

There would be no changes in the fundamental characteristics of the rays. (correct)
The rays would have an increased capacity to raise the temperature of the body.
The rays would be deflected towards negative plates instead of postive plates.
The rays would travel in a curved path instead of straight lines.

What significant conclusion about the composition of matter was drawn from the observation that cathode rays are always the same?

That the mass of an atom depends entirely on the composition of the cathode ray.
That all gases must have a uniform chemical composition.
That all materials possess the same fundamental, negatively charged particles. (correct)
That all elements have differing but similar negatively charged particles.

Based on the text, what is the primary distinction between cathode rays and canal rays?

Canal rays travel in the opposite direction to cathode rays. (B) Signup and view all the answers

What experimental setup is required to observe canal rays in a gas discharge tube?

A gas discharge tube with a perforated cathode. (C) Signup and view all the answers

Which of the following best describes Dalton's view of the atom?

A solid, indivisible sphere of uniform density. (D) Signup and view all the answers

What evidence led J.J. Thomson to propose the plum pudding model of the atom?

The discovery of electrons, which he considered a subatomic particle. (B) Signup and view all the answers

What is the primary observation that led to the discovery of cathode rays?

The emission of rays from the cathode. (B) Signup and view all the answers

Which property of cathode rays was critical to concluding that they carry a negative charge?

Their deflection towards a positive electrode. (D) Signup and view all the answers

What was the significance of using a low-pressure gas in the discovery of cathode rays?

To maximize the emission and movement of the cathode rays. (D) Signup and view all the answers

Besides cathode rays, what other type of rays did Goldstein discover in the discharge tube?

Canal rays. (A) Signup and view all the answers

How do canal rays and cathode rays differ in their charge?

Canal rays are positively charged, and cathode rays are negatively charged. (A) Signup and view all the answers

What was the main difference between the experimental setup used for the discovery of cathode rays and canal rays?

Presence of a perforated cathode. (C) Signup and view all the answers

Which statement best describes the relationship between the composition of canal rays and the gas within a discharge tube?

The mass and charge of canal ray particles vary depending on the specific gas in the tube. (C) Signup and view all the answers

How did the existence of canal rays contribute to our understanding of atomic structure?

They demonstrated that atoms have a positively charged component. (C) Signup and view all the answers

What is the crucial role of cathode rays in the origination of canal rays inside a discharge tube?

Cathode rays collide with and ionize the gas molecules, creating canal rays. (B) Signup and view all the answers

Apart from their charge, what essential property distinguishes neutrons from protons?

Neutrons are known for their highly penetrating property due to lack of charge. (A) Signup and view all the answers

Which experimental process led to the discovery of neutrons?

Bombarding beryllium with alpha particles. (D) Signup and view all the answers

In Rutherford's alpha scattering experiment, what did the fact that some alpha particles bounced back indicate?

Atoms are mostly empty space with a small dense positive core. (D) Signup and view all the answers

What was the original hypothesis that motivated the search for the neutron?

To explain the difference in mass between atoms. (D) Signup and view all the answers

What is the mass of a canal ray particle when the lightest gas (hydrogen) is used in a discharge tube?

Identical to mass of a proton. (C) Signup and view all the answers

What was the key conclusion from Rutherford's gold foil experiment regarding the structure of the atom?

Most of the atom is empty space with a dense nucleus. (A) Signup and view all the answers

During Rutherford's experiment, how many alpha particles were reported to be deflected at large angles?

Only a few out of 20,000 particles. (C) Signup and view all the answers

What purpose did the zinc sulfide coated screen serve in Rutherford's experiment?

To detect the alpha particles and their scattering. (A) Signup and view all the answers

What type of particles were used in Rutherford's experiment to probe the structure of the atom?

Alpha particles (A) Signup and view all the answers

How did Rutherford's findings influence the understanding of atomic structure?

They led to the conclusion that the atom has a positively charged nucleus. (D) Signup and view all the answers

Dalton's Atomic Theory

Dalton proposed that atoms are indivisible, hard, dense spheres. Atoms of the same element are identical. They combine in various ways to form compounds.

Discovery of Protons

Positively charged particles (protons) were discovered by Goldstein in 1886.

Discovery of Electrons

J.J. Thomson discovered negatively charged particles (electrons) in 1897.

Thomson's Plum Pudding Model

Thomson's model proposes that atoms are solid, positively charged structures with embedded negatively charged particles (electrons), like plums in a pudding.