SCIE 3301 Exam 3 practice questions

A student says air is not matter because it cannot be seen. Which response best challenges the claim? (SG 9.1)

Air has mass and occupies space.

Distinguish between an atom and an element. (SG 9.1)

Atom is one unit in a collection in a element

How many types of atoms can you expect to find in a pure sample of any element? (SG 9.1)

Only one type

A neutral atom has 8 protons. Which statement must be true? (SG 9.2)

It has 8 electrons

Atom A has 11 protons and 12 neutrons. Atom B has 11 protons and 13 neutrons. How are they related? (SG 9.3)

They are isotopes of the same element.

Two atoms each have a mass number of 20. One has 10 protons and the other has 9. What can you conclude? (SG 9.3)

They are different elements because their proton counts differ.

Two elements in the same group each have one valence electron. Which prediction is best supported? (SG 9.4)

They may have similar chemical behaviors.

An unknown gas has bright lines at 430 nm and 610 nm. Gas X has lines at 430 and 610 nm; Gas Y has lines at 430 and 580 nm. If the unknown is one of these gases, which conclusion is supported? (SG 9.5)

Gas X, because both observed lines match.

How would you describe light generated by heating pure elements if it was observed through a prism or spectroscope? (SG 9.5)

You would see a series of very sharp lines of emitted light.

A liquid takes the shape of a new container, but a solid keeps its shape. Why? (SG 11.1)

Liquid particles move past one another; solid particles vibrate around fixed positions.

A sample has a mass of 30 g and a volume of 10 cm³. What is its density? (SG 11.2)

3 g/cm³

A student claims O₂ must be a compound because it has two bonded atoms. Which response is best? (SG 11.3)

O₂ is an element because both atoms are oxygen.

Sugar completely dissolves in water, and the liquid looks the same throughout. How is it classified? (SG 11.3)

Homogeneous mixture

A wet sidewalk dries without its water boiling. Which explanation fits? (SG 11.4)

Some surface water molecules escape into the air.

Which property describes a substance’s ability to form a new substance? (SG 11.5)

Reactivity with oxygen

A student melts ice, and testing shows both solid and liquid are water. What does the evidence support? (SG 11.6)

A physical change occurred because the substance remained water.

Which is the clearest example of a chemical change? (SG 11.6)

An iron nail forms rust

Which revision balances H₂ + Cl₂ → HCl without changing the substances? (SG 13.1)

H₂ + Cl₂ → 2HCl

A reaction in an open container produces gas. The container and contents have a mass of 90 g before and 87 g after. No liquid spills. What best explains the change? (SG 13.2)

Approximately 3 g of gas escaped.

Two substances react in an insulated cup, and the temperature rises from 21°C to 28°C. Which explanation fits? (SG 13.3)

The reaction was exothermic and warmed the mixture.

Equal masses of a powdered solid and a large chunk react in the same acid. Why does the powder react faster?

It exposes more surface area.

Carbon monoxide enters a catalytic converter and carbon dioxide leaves. What does this support?

A chemical reaction formed a different substance

Adding base raises an acidic solution’s pH from 2 to 4. What can be concluded? (SG 13.5)

It is less acidic but remains acidic.

An oxygen atom gains electrons. What has happened to it? (SG 13.6)

It has been reduced.

A student says bacteria cannot pass on genetic information because they have no nucleus. Which response challenges this? (SG 15.1)

Bacteria contain DNA even without a nucleus.

Which structure regulates movement of substances into and out of a cell? (SG 15.2)

Cell membrane

Which plant-cell structure captures sunlight to help make sugars? (SG 15.2)

Chloroplast

How can fermentation help a muscle cell when oxygen is limited? (SG 15.3)

It helps glycolysis continue.

Which process uses carbon dioxide, water, and light to produce glucose and oxygen? (SG 15.4)

Photosynthesis

During which cell-cycle phase is DNA replicated? (SG 15.5)

S phase

What does S stand for in the cell cycle’s S phase (SG 15.5)

Synthesis of DNA

Which statement describes a scientific theory? (SG B1)

A broad explanation supported by a large body of evidence

A student travels 18 meters in 3 seconds. What is the average speed? (SG B2)

A) 6 m/s

A swimmer pushes water backward and moves forward because: (SG B2)

The water pushes the swimmer forward.

Two identical batteries are connected in series in the same direction. Compared with one battery, the total voltage: (SG B3)

Increases

Which measurement represents wavelength? (SG B3)

Distance from one crest to the next