FSQ 7

Which sentence correctly explains the change that occurs when ice melts?

• Ice melting is a physical change, and the state of the substance remains the same.

• Ice melting is a physical change, and the mass of the substance remains the same.

• Ice melting is a chemical change, and the state of the substance remains the same.

• Ice melting is a chemical change, and the mass of the substance remains the same.

Answer explanation

Ice melting is a physical change because it alters the state from solid to liquid without changing its chemical composition. The mass remains the same, as no substance is lost or gained during the process.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Which of the following statements regarding physical and chemical changes is true?

• Both physical and chemical changes alter the molecular structure of a substance.

• Neither physical nor chemical changes alter the molecular structure of a substance.

• Physical changes alter the composition of a molecular structure, while chemical changes do not.

• Chemical changes alter the composition of a molecular structure, while physical changes do not.

Answer explanation

Chemical changes involve breaking and forming bonds, altering the molecular structure and composition of a substance. In contrast, physical changes do not change the molecular structure, only the state or appearance.

Tags

NGSS.MS-PS1-4

Which question can be used to identify a physical property of an element?

• Does a magnet attract the element?

• Does rust form when the element is exposed to oxygen?

• Do bubbles form when the element is mixed with an acid?

• Does the element burn when held over a Bunsen burner flame?

Answer explanation

The question 'Does a magnet attract the element?' identifies a physical property, specifically magnetism. The other options relate to chemical properties, such as reactivity and combustion.

A teacher heats water in a test tube over a small flame. Which test tube setup best demonstrates the Law of Conservation of Mass?

• A

• B

• C

• D

Answer explanation

Choice B best demonstrates the Law of Conservation of Mass as it likely shows a closed system where no mass is lost or gained during the heating process, illustrating that the total mass remains constant.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

John is performing an experiment in which a solution alternates between a clear color and a bluish-purple color at a regular time interval. He observes that the time interval between color changes is 30 seconds (s). Sally replicates the experiment with the same solution, but at a temperature that is 10 degrees Celsius (°C) higher. What is the most likely time interval between color changes at this higher temperature?

• 15 s

• 30 s

• 45 s

• 60 s

Answer explanation

Increasing the temperature typically speeds up reactions, leading to faster color changes. Since the original interval is 30 s, a 10 °C increase likely halves the time, resulting in a new interval of 15 s.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Students were studying a graph showing the phase changes of a substance. The graph is shown below. Which statement best describes the data shown?

• Q shows no change in temperature or absorbed heat and no phase change.

• R shows an increase in absorbed heat and a phase change from solid to gas.

• P shows an increase of kinetic energy and a phase change from solid to liquid.

• S shows no change in temperature and shows a phase change from liquid to gas.

Answer explanation

Choice S is correct because it indicates a phase change from liquid to gas (vaporization) occurs at a constant temperature, which is characteristic of phase changes, while the other options misrepresent the data.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

In any chemical reaction, the mass of the reactants equals the mass of the products. This result forms the basis of the Law of Conservation of Mass. Which statement correctly explains why this is a law, rather than a theory?

• It has more scientific evidence supporting it.

• It has both independent and dependent variables.

• It has been tested with the latest laboratory balances, which are very accurate.

• It describes a repeatedly observed relationship, but it does not offer an explanation.

Answer explanation

The Law of Conservation of Mass is a law because it describes a consistently observed relationship in nature, stating that mass is conserved in reactions, without providing a mechanism or explanation for why this occurs.

Tags

NGSS.MS-PS1-5