NYSTCE ATAS NYSTCE Chemistry 5 — Questions and Answers
Question 1: Which of the following correctly describes isotopes of the same element?
- Same number of neutrons, different number of protons
- Same number of protons, different number of neutrons (Correct answer)
- Same atomic mass, different atomic number
- Same number of electrons, different number of protons
Correct answer: Same number of protons, different number of neutrons
Isotopes of an element have the same atomic number (protons) but differ in the number of neutrons, giving them different mass numbers.
Question 2: Which of the following is an example of a homogeneous mixture?
- Salad dressing (oil and vinegar)
- Soil
- Salt dissolved in water (Correct answer)
- Sand and gravel
Correct answer: Salt dissolved in water
Salt dissolved in water forms a homogeneous mixture (solution) because the composition is uniform throughout the liquid.
Question 3: In a single replacement reaction such as Zn + 2HCl → ZnCl₂ + H₂, zinc replaces hydrogen because:
- Zinc is less reactive than hydrogen
- Zinc is more reactive than hydrogen in the activity series (Correct answer)
- Hydrogen is a metal
- The reaction requires a catalyst
Correct answer: Zinc is more reactive than hydrogen in the activity series
In the activity series, zinc is above hydrogen, meaning it is more reactive and can displace hydrogen from acid solutions.
Question 4: Which state of matter has a definite volume but takes the shape of its container?
- Solid
- Liquid (Correct answer)
- Gas
- Plasma
Correct answer: Liquid
Liquids have a fixed volume because their particles are close together, but they flow to take the shape of any container.
Question 5: The Avogadro's number (6.02 × 10²³) represents the number of particles in:
- One gram of any element
- One liter of any gas
- One mole of a substance (Correct answer)
- One formula unit of an ionic compound
Correct answer: One mole of a substance
Avogadro's number defines the mole: one mole of any substance contains 6.02 × 10²³ representative particles (atoms, molecules, or formula units).
Question 6: Which of the following best represents a catalyst's role in a chemical reaction?
- It is consumed and becomes part of the products
- It increases the activation energy required
- It lowers the activation energy without being consumed (Correct answer)
- It changes the products of the reaction
Correct answer: It lowers the activation energy without being consumed
A catalyst speeds up a reaction by providing an alternative pathway with lower activation energy, and it is not permanently consumed in the process.
Question 7: When a teaching assistant supports a student struggling to read a chemical equation, which scaffold is MOST helpful?
- Read the equation aloud using element names and coefficients (Correct answer)
- Tell the student the answer directly to save time
- Ask the student to memorize all element symbols first
- Skip the equation and move to a different topic
Correct answer: Read the equation aloud using element names and coefficients
Reading the equation aloud using element names and coefficients helps students decode chemical notation by connecting symbols to their meaning.
NYSTCE ATAS NYSTCE Chemistry 5
Which of the following correctly describes isotopes of the same element?