ILTS Chemistry Certification
Examination Questions and Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. The atomic number of an element equals the number of:
A. Neutrons
B. Electrons and neutrons
C. Protons and neutrons
D. Protons
Correct Answer: D. Protons
Rationale: The atomic number is defined as the number of protons in the nucleus
and identifies the element.
2. Which subatomic particle has a negative charge?
A. Proton
B. Neutron
C. Nucleus
D. Electron
Correct Answer: D. Electron
Rationale: Electrons carry a negative electrical charge and are located outside the
nucleus.
,3. The mass number of an atom is the sum of:
A. Electrons and protons
B. Electrons and neutrons
C. Protons only
D. Protons and neutrons
Correct Answer: D. Protons and neutrons
Rationale: The mass number represents the total number of nucleons (protons and
neutrons).
4. Atoms of the same element with different numbers of neutrons are called:
A. Ions
B. Compounds
C. Molecules
D. Isotopes
Correct Answer: D. Isotopes
Rationale: Isotopes have the same number of protons but different neutron
numbers.
5. A positively charged ion is called a:
A. Anion
B. Isotope
C. Molecule
D. Cation
Correct Answer: D. Cation
Rationale: Cations form when atoms lose electrons and become positively
charged.
6. A negatively charged ion is called an:
,A. Atom
B. Cation
C. Proton
D. Anion
Correct Answer: D. Anion
Rationale: Anions form when atoms gain electrons.
7. Which scientist developed the modern atomic theory?
A. Rutherford
B. Bohr
C. Thomson
D. John Dalton
Correct Answer: D. John Dalton
Rationale: Dalton proposed that matter is composed of atoms and developed the
first modern atomic theory.
8. Which experiment demonstrated the existence of a small, dense atomic
nucleus?
A. Cathode ray experiment
B. Oil drop experiment
C. Flame test
D. Gold foil experiment
Correct Answer: D. Gold foil experiment
Rationale: Rutherford's gold foil experiment showed that atoms contain a
concentrated nucleus.
9. Electrons in the outermost energy level are called:
, A. Core electrons
B. Nuclear electrons
C. Excited electrons
D. Valence electrons
Correct Answer: D. Valence electrons
Rationale: Valence electrons determine chemical bonding and reactivity.
10. The maximum number of electrons in the first energy level is:
A. 1
B. 4
C. 8
D. 2
Correct Answer: D. 2
Rationale: The first energy level contains only the 1s orbital, which holds two
electrons.
11. The periodic table is arranged according to increasing:
A. Density
B. Atomic mass
C. Number of neutrons
D. Atomic number
Correct Answer: D. Atomic number
Rationale: Elements are arranged by increasing number of protons.
12. Elements in the same group have similar:
A. Atomic masses
B. Numbers of shells
Examination Questions and Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. The atomic number of an element equals the number of:
A. Neutrons
B. Electrons and neutrons
C. Protons and neutrons
D. Protons
Correct Answer: D. Protons
Rationale: The atomic number is defined as the number of protons in the nucleus
and identifies the element.
2. Which subatomic particle has a negative charge?
A. Proton
B. Neutron
C. Nucleus
D. Electron
Correct Answer: D. Electron
Rationale: Electrons carry a negative electrical charge and are located outside the
nucleus.
,3. The mass number of an atom is the sum of:
A. Electrons and protons
B. Electrons and neutrons
C. Protons only
D. Protons and neutrons
Correct Answer: D. Protons and neutrons
Rationale: The mass number represents the total number of nucleons (protons and
neutrons).
4. Atoms of the same element with different numbers of neutrons are called:
A. Ions
B. Compounds
C. Molecules
D. Isotopes
Correct Answer: D. Isotopes
Rationale: Isotopes have the same number of protons but different neutron
numbers.
5. A positively charged ion is called a:
A. Anion
B. Isotope
C. Molecule
D. Cation
Correct Answer: D. Cation
Rationale: Cations form when atoms lose electrons and become positively
charged.
6. A negatively charged ion is called an:
,A. Atom
B. Cation
C. Proton
D. Anion
Correct Answer: D. Anion
Rationale: Anions form when atoms gain electrons.
7. Which scientist developed the modern atomic theory?
A. Rutherford
B. Bohr
C. Thomson
D. John Dalton
Correct Answer: D. John Dalton
Rationale: Dalton proposed that matter is composed of atoms and developed the
first modern atomic theory.
8. Which experiment demonstrated the existence of a small, dense atomic
nucleus?
A. Cathode ray experiment
B. Oil drop experiment
C. Flame test
D. Gold foil experiment
Correct Answer: D. Gold foil experiment
Rationale: Rutherford's gold foil experiment showed that atoms contain a
concentrated nucleus.
9. Electrons in the outermost energy level are called:
, A. Core electrons
B. Nuclear electrons
C. Excited electrons
D. Valence electrons
Correct Answer: D. Valence electrons
Rationale: Valence electrons determine chemical bonding and reactivity.
10. The maximum number of electrons in the first energy level is:
A. 1
B. 4
C. 8
D. 2
Correct Answer: D. 2
Rationale: The first energy level contains only the 1s orbital, which holds two
electrons.
11. The periodic table is arranged according to increasing:
A. Density
B. Atomic mass
C. Number of neutrons
D. Atomic number
Correct Answer: D. Atomic number
Rationale: Elements are arranged by increasing number of protons.
12. Elements in the same group have similar:
A. Atomic masses
B. Numbers of shells
