Question

question 1 (1 point)
(02.01 mc)
rutherford’s famous gold foil experiments shot heavy particles at a thin sheet of gold foil. what did he observe, and why did these observations eventually result in the addition of a nucleus to the atomic model?
\ta some of the heavy particles bounced off the foil because there are positive particles spread throughout the atom.
\tb some of the heavy particles bounced off the foil because there is a dense positive area in the atom.
\tc the heavy particles all passed straight through the foil because the atoms are mostly empty space.
\td the heavy particles all bounced off the foil because the subatomic particles have mass and volume.

question 2 (1 point)
(02.01 mc)
in rutherford’s famous experiment, he shot heavy, fast moving, positive alpha particles at a thin gold foil. based on thomson’s plum pudding model of the atom, what did rutherford expect to happen, and why?
\ta all the alpha particles would be deflected by the foil because of the even distribution of mass and charge throughout the atom.
\tb all the alpha particles would pass straight through the foil because of the even distribution of mass and charge throughout the atom.
\tc most of the alpha particles would become embedded in the foil because they are attracted to the negative electrons in the atom.
\td some of the alpha particles would be deflected and some would pass through because of the negative charge of the electron cloud.

question 3 (1 point)
(02.01 mc)
what evidence from j.j. thomson’s experiments with the cathode ray led to the plum pudding model of the atom?
\ta the beam was attracted to a positive charge and repelled by a negative charge, showing that atoms contain small, negatively charged particles.
\tb the beam was attracted to a negative charge and repelled by a positive charge, showing that atoms contain small, positively charged particles.
\tc the beam was positively charged and had significant mass, showing that atoms have a positive, dense nucleus.
\td the beam was neutral and had significant mass, showing that atoms contain neutral particles in the nucleus.

Explanation:

Question 1

Rutherford's gold foil experiment: Most alpha particles passed through, some bounced back. Bouncing back happened because a dense positive nucleus (the nucleus) repelled the positive alpha particles. Option a says positive particles spread (wrong, plum pudding model idea), option c says all passed (wrong, some bounced), option d says all bounced (wrong). So option b is correct.

Thomson's plum pudding model had mass and charge evenly distributed. So Rutherford, based on this, expected alpha particles (positive) to pass straight through as the even distribution wouldn't strongly deflect them. Option a says all deflected (wrong, even distribution wouldn't cause strong deflection), option c says embedded (alpha particles are positive, electrons negative but plum pudding is even, not attraction to embed), option d says some deflected due to electron cloud (plum pudding has no electron cloud concept, charge is even). So option b is correct.

J.J. Thomson's cathode ray experiment: The cathode ray (electrons) was attracted to positive charge and repelled by negative charge, showing atoms have small negative particles (electrons). Option b says attracted to negative (wrong, electrons are negative, so attracted to positive), option c says beam positive (wrong, cathode ray is negative), option d says beam neutral (wrong, cathode ray is negative). So option a is correct.

Answer:

b. Some of the heavy particles bounced off the foil because there is a dense positive area in the atom.

Question 2