CHEM134 C003 LESSON 2: ATOMS,
MOLECULES, AND IONS QUESTIONS
AND ANSWERS WITH VERIFIED
SOLUTIONS 2026/2027 UPDATE. JUST
RELEASED
1. What was the primary conclusion of Rutherford’s gold foil experiment?
A. Electrons move in circular orbits around the nucleus.
B. Atoms consist of a diffuse cloud of positive charge.
C. Neutrons are located in the center of the atom.
D. Most of the atom’s mass and positive charge is concentrated in a tiny nucleus.
Answer: D
Conceptual Explanation: Rutherford’s experiment showed that most alpha particles
passed through, but a few were deflected at large angles, indicating a dense, positively
charged nucleus.
2. Which subatomic particle was discovered by J.J. Thomson using a cathode ray tube?
A. Electron
,B. Proton
C. Neutron
D. Positron
Answer: A
Conceptual Explanation: J.J. Thomson’s experiments with cathode rays led to the
discovery of the electron and determined its charge-to-mass ratio.
3. Robert Millikan’s oil-drop experiment was significant because it determined:
A. The mass of a proton.
B. The specific charge of the nucleus.
C. The fundamental charge of an electron.
D. The existence of isotopes.
Answer: C
Conceptual Explanation: Millikan measured the charge of individual oil drops to calculate
the charge of a single electron.
4. How many neutrons are present in an atom of Carbon-14?
A. 6
B. 8
C. 14
, D. 12
Answer: B
Conceptual Explanation: Carbon has an atomic number of 6. For Carbon-14, the number
of neutrons is the mass number (14) minus the atomic number (6), which equals 8.
5. The identity of a chemical element is determined by the number of:
A. Neutrons
B. Protons
C. Valence electrons
D. Electrons
Answer: B
Conceptual Explanation: The atomic number (Z), which is the number of protons in the
nucleus, uniquely identifies an element.
6. Isotopes are atoms of the same element that differ in:
A. Number of neutrons
B. Number of protons
C. Chemical properties
D. Atomic number
Answer: A
MOLECULES, AND IONS QUESTIONS
AND ANSWERS WITH VERIFIED
SOLUTIONS 2026/2027 UPDATE. JUST
RELEASED
1. What was the primary conclusion of Rutherford’s gold foil experiment?
A. Electrons move in circular orbits around the nucleus.
B. Atoms consist of a diffuse cloud of positive charge.
C. Neutrons are located in the center of the atom.
D. Most of the atom’s mass and positive charge is concentrated in a tiny nucleus.
Answer: D
Conceptual Explanation: Rutherford’s experiment showed that most alpha particles
passed through, but a few were deflected at large angles, indicating a dense, positively
charged nucleus.
2. Which subatomic particle was discovered by J.J. Thomson using a cathode ray tube?
A. Electron
,B. Proton
C. Neutron
D. Positron
Answer: A
Conceptual Explanation: J.J. Thomson’s experiments with cathode rays led to the
discovery of the electron and determined its charge-to-mass ratio.
3. Robert Millikan’s oil-drop experiment was significant because it determined:
A. The mass of a proton.
B. The specific charge of the nucleus.
C. The fundamental charge of an electron.
D. The existence of isotopes.
Answer: C
Conceptual Explanation: Millikan measured the charge of individual oil drops to calculate
the charge of a single electron.
4. How many neutrons are present in an atom of Carbon-14?
A. 6
B. 8
C. 14
, D. 12
Answer: B
Conceptual Explanation: Carbon has an atomic number of 6. For Carbon-14, the number
of neutrons is the mass number (14) minus the atomic number (6), which equals 8.
5. The identity of a chemical element is determined by the number of:
A. Neutrons
B. Protons
C. Valence electrons
D. Electrons
Answer: B
Conceptual Explanation: The atomic number (Z), which is the number of protons in the
nucleus, uniquely identifies an element.
6. Isotopes are atoms of the same element that differ in:
A. Number of neutrons
B. Number of protons
C. Chemical properties
D. Atomic number
Answer: A
