Question

question 1 (1 point)
(02.01 lc)
which scientist proposed the model of an atom as a solid sphere?
a john dalton
b niels bohr
c ernest rutherford
d william crookes

question 2 (1 point)
(02.01 mc)
which of the following experimental observations proved that dalton’s postulate about the indivisibility of the atom was flawed?
a cathode rays inside the tube deflected towards a negatively charged rod.
b cathode rays inside the tube deflected towards a positively charged rod.
c a few alpha particles bounced back during the scattering experiment.
d all alpha particles went straight during the scattering experiment.

question 3 (1 point)
(02.01 mc)
when rutherford used fast moving alpha particles, which are positively charged, and passed them through a thin piece of gold foil in his gold - foil experiment, he believed that the particles would pass through the atoms of gold foil because the mass and charge of the atom was evenly distributed in the atom. his results, however, showed that some of the alpha particles were deflected, including some which were deflected directly back at the source of the alpha particles. this led him to conclude that
a the positive charges in the atom were not evenly distributed but instead concentrated in a small, dense nucleus
b the positive charges in the atom were evenly distributed throughout the atom
c the negative charges in the atom were not evenly distributed but instead concentrated in a small, dense nucleus
d the negative charges in the atom were evenly distributed throughout the atom

Explanation:

Question 1

John Dalton proposed the atomic model where atoms are considered solid, indivisible spheres. Niels Bohr proposed the planetary model, Ernest Rutherford the nuclear model, and William Crookes worked on cathode rays but not the solid - sphere atomic model.

Dalton postulated atoms are indivisible. Cathode ray experiments (where cathode rays, made of electrons, deflect towards a positively charged rod) showed atoms have sub - atomic particles (electrons), proving Dalton's postulate wrong. Option a is incorrect as electrons (cathode rays) should be attracted to positive. Options c and d are about Rutherford's alpha - particle scattering experiment, related to the nucleus, not atom divisibility.

In Rutherford's gold - foil experiment, most alpha particles passed through, some deflected, a few bounced back. This showed that the positive charge (and most mass) of the atom is concentrated in a small, dense nucleus (since alpha particles (positive) were deflected by positive charges). Option b is what Rutherford thought initially (wrong), option c and d are wrong as negative charges (electrons) are not in the nucleus and are distributed as electron cloud.

Answer:

a. John Dalton

Question 2