Practice Test 1 Complete (Questions 1–100) Send “Start Practice Test 2” to begin the second set (Questions 101–200) with new, non-repeated questions. Which statement best describes an isotope?

Atoms with the same number of protons but different neutrons

Atoms with the same number of neutrons but different protons

Atoms with different electrons and protons

Atoms with identical mass numbers

GACE Chemistry (6–12) (712)

Free GACE Chemistry (6–12) (712) Practice Questions

10 sample questions for the GACE Chemistry (6–12) (712), with the correct answer and an explanation for each. No account needed. Try each one before you open the answer.

Sections covered on the exam: Atomic Structures and Properties, Multi-atomic Structures and Properties, Chemical Reactions, Energy Changes.

Question 1 · Atomic Structures and Properties
An atom of magnesium has an atomic number of 12 and a mass number of 24. How many neutrons does this atom contain?
- A.10
- B.24
- C.12
- D.36
Show answer and explanation
Answer: C. 12
The number of neutrons is found by subtracting the atomic number from the mass number. Mass number = protons + neutrons Atomic number = protons So: 24 − 12 = 12 neutrons
Question 2 · Atomic Structures and Properties
This changes the element into the next one on the periodic table.
Which isotope notation represents carbon-14?
- A.⁶₁₂C
- B.⁶₁₄C
- C.¹⁴₁₂C
- D.¹⁴₆C
Show answer and explanation
Answer: D. ¹⁴₆C
In isotope notation: The top number is the mass number The bottom number is the atomic number
Question 3 · Multi-atomic Structures and Properties
Which gas law states that pressure is inversely proportional to volume?
- A.Charles’s law
- B.Ideal gas law
- C.Avogadro’s law
- D.Boyle’s law
Show answer and explanation
Answer: D. Boyle’s law
Boyle’s law: P ∝ 1/V (at constant temperature) As volume increases, pressure decreases.
Question 4 · Chemical Reactions
Which factor does NOT affect equilibrium position?
- A.Temperature
- B.Catalyst
- C.Pressure
- D.Concentration
Show answer and explanation
Answer: B. Catalyst
Catalysts:
Question 5 · Energy Changes
Products have higher energy than reactants
What does the first law of thermodynamics state?
- A.Energy is conserved
- B.Energy is created
- C.Energy is destroyed
- D.Energy disappears
Show answer and explanation
Answer: A. Energy is conserved
Energy cannot be created or destroyed. It only changes form
Question 6 · Atomic Structures and Properties
Practice Test 1 Complete (Questions 1–100)
Send “Start Practice Test 2” to begin the second set (Questions 101–200) with new, non-repeated questions.
Which statement best describes an isotope?
- A.Atoms with the same number of neutrons but different protons
- B.Atoms with different electrons and protons
- C.Atoms with the same number of protons but different neutrons
- D.Atoms with identical mass numbers
Show answer and explanation
Answer: C. Atoms with the same number of protons but different neutrons
Isotopes are atoms of the same element (same atomic number) but with different numbers of neutrons, resulting in different mass numbers.
Question 7 · Atomic Structures and Properties
Which particle has highest mass?
- A.Electron
- B.Neutron
- C.Proton
- D.Photon
Show answer and explanation
Answer: B. Neutron
Neutron slightly heavier than proton.
Question 8 · Energy Changes
Which state has highest compressibility?
- A.Solid
- B.Gas
- C.Liquid
- D.Plasma
Show answer and explanation
Answer: B. Gas
Gas particles are far apart, allowing compression.
Question 9 · Chemical Reactions
Which does NOT affect equilibrium?
- A.Pressure
- B.Catalyst
- C.Temperature
- D.Concentration
Show answer and explanation
Answer: B. Catalyst
Catalyst speeds reactions but does not shift equilibrium.
Question 10 · Energy Changes
Energy cannot be created or destroyed. This is:
- A.First law
- B.Law of motion
- C.Third law
- D.Second law
Show answer and explanation
Answer: A. First law
Energy is conserved.

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