Which of the following statements does not describe a physical property?
A) Sparks are created when sodium metal is added to water.
B) A strip of magnesium metal weighs 7.49 grams.
C) Snow forms in the clouds via deposition.
D) Mercury is a liquid at room temperature.
The correct answer and explanation is :
The correct answer is A) Sparks are created when sodium metal is added to water.
Explanation:
A physical property is a characteristic of a substance that can be observed or measured without changing the substance’s chemical identity. These properties describe the physical state or appearance of a substance, such as color, mass, density, temperature, and state of matter. Examples of physical properties include melting point, boiling point, density, solubility, and electrical conductivity.
Let’s review each option to clarify why option A is the correct choice.
- A) Sparks are created when sodium metal is added to water.
- This is not a physical property but a chemical property. It describes how sodium reacts with water, leading to a chemical reaction that produces sparks, heat, and hydrogen gas. A chemical property refers to a substance’s ability to undergo a specific chemical change or reaction. The reaction of sodium with water is an example of a chemical reaction because the sodium is chemically altered as it reacts with water, forming sodium hydroxide and hydrogen gas.
- B) A strip of magnesium metal weighs 7.49 grams.
- This is a physical property. Weight or mass is a physical property because it can be measured without changing the chemical identity of the magnesium metal. It involves a quantitative measure of the amount of matter in the strip.
- C) Snow forms in the clouds via deposition.
- This is a physical property. Deposition refers to the phase change where water vapor in the air changes directly into solid snow without becoming liquid. This process involves a change in physical state from gas to solid, which is a physical change.
- D) Mercury is a liquid at room temperature.
- This is a physical property. The state of matter (liquid in this case) at room temperature is a physical property that can be observed without altering the chemical composition of mercury.
Thus, option A, describing a chemical reaction, is the only one that does not reflect a physical property.