What role does the centromere play in cellular reproduction? OPTIONS:
- It is the area where microtubules are formed.
- It is the area where the nucleus is during cell division.
- It is the area of alignment for the chromosomes.
- It is the area of attachment for chromatids.
A: It is the area of attachment for chromatids.

What are the names of the products in the chemical equation shown below? HCl + NaHCO_{3} -> NaCl + CO_{2} + H_{2}O OPTIONS:
- hydrochloric acid and sodium carbonate
- sodium chloride, carbon dioxide, and water
- hydrogen chloride and sodium bicarbonate
- sodium chloride, carbon monoxide, and dihydrogen oxide
A: sodium chloride, carbon dioxide, and water

During a lab investigation a scientist heats a solid substance. The scientist observes that the solid has two different melting points. The scientist is able to separate the two resulting liquids. Which statement best classifies the original solid substance? OPTIONS:
- It was an atom.
- It was a mixture.
- It was an element.
- It was a compound.
A: It was a mixture.

A group of students was preparing an activity to determine whether certain materials will float or sink when placed on water. Before the experiment started, one student said, "I think the sponge will float." This statement was OPTIONS:
- a conclusion
- a fact
- an observation
- a prediction
A:
a prediction