CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
Which process involves sharing valence electrons between atoms?
A. Radioactive decay only
B. Neutron capture only
C. Nuclear fission
D. Covalent bonding
Correct Answer: D
Covalent bonds form when atoms share pairs of valence electrons.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
Which quantum number primarily identifies an electron's main energy level?
A. Atomic mass number
B. Oxidation number only
C. Principal quantum number
D. Avogadro number
Correct Answer: C
The principal quantum number n labels the main electron shell or energy level.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
Which scientist's experiments are associated with determining the electron's charge-to-mass ratio?
A. Niels Bohr only for radioactivity
B. James Chadwick
C. Ernest Rutherford only for neutron discovery
D. J. J. Thomson
Correct Answer: D
J. J. Thomson's cathode-ray experiments established the electron and measured its charge-to-mass ratio.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
Which subatomic particle has a mass much smaller than that of a proton?
A. Electron
B. Neutron
C. Alpha particle
D. Nucleus
Correct Answer: A
The electron's mass is about 1/1836 of the proton mass.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
What happens when a neutral atom loses an electron?
A. It becomes an isotope automatically
B. It becomes a neutron
C. Its atomic number becomes zero
D. It becomes a positively charged ion
Correct Answer: D
Loss of electrons leaves more protons than electrons, producing a cation.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
What happens when a neutral atom gains an electron?
A. It becomes a neutron
B. It becomes a negatively charged ion
C. Its nucleus disappears
D. It becomes a proton
Correct Answer: B
Gaining one or more electrons gives an atom a net negative charge, forming an anion.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
A neutral atom has equal numbers of electrons and which particles?
A. Photons
B. Neutrons
C. Protons
D. Isotopes
Correct Answer: C
Equal positive and negative charges make the atom electrically neutral.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
Which electron group mainly determines an element's chemical bonding behavior?
A. All nucleons equally
B. Valence electrons
C. Nuclear protons only
D. Core neutrons
Correct Answer: B
Valence electrons are the outer electrons involved most directly in bonding and reactions.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
Where are electrons found in an atom?
A. In the nucleus as heavy particles
B. Only inside neutrons
C. Inside protons
D. In orbitals or electron clouds around the nucleus
Correct Answer: D
Electrons occupy quantum states described by orbitals around the nucleus.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Electrons
What is the electric charge of an electron?
A. Neutral
B. Negative
C. Positive
D. Variable positive only
Correct Answer: B
An electron carries one elementary unit of negative charge.