Which statement is false?
A) Different mixtures of the same two substances must have the same composition.
B) A mixture of sea sand and table salt is an example of a heterogeneous mixture.
C) An example of a homogeneous mixture is one prepared by mixing drinking alcohol and water.
D) A compound is a substance that can be decomposed into two or more simpler substances by chemical means.
The correct answer and explanation is :
The false statement is:
A) Different mixtures of the same two substances must have the same composition.
Explanation:
A) Different mixtures of the same two substances must have the same composition.
This statement is false because mixtures, by definition, do not have a fixed composition. The proportions of the components in a mixture can vary, depending on how much of each substance is combined. For example, a mixture of salt and sand can have different amounts of salt and sand, resulting in different compositions. The ratio of components in a mixture is not fixed, and thus, different mixtures of the same substances can have different compositions.
B) A mixture of sea sand and table salt is an example of a heterogeneous mixture.
This statement is true because a heterogeneous mixture is one in which the components are not uniformly distributed. In the case of sea sand and table salt, the sand and salt are not evenly mixed, and you can visually distinguish the two substances. The composition of the mixture can vary from one part to another, making it heterogeneous.
C) An example of a homogeneous mixture is one prepared by mixing drinking alcohol and water.
This statement is true because a homogeneous mixture is one in which the components are uniformly distributed. When drinking alcohol (ethanol) is mixed with water, the two substances form a single phase, and the mixture has a uniform composition throughout. It is an example of a solution, which is a type of homogeneous mixture.
D) A compound is a substance that can be decomposed into two or more simpler substances by chemical means.
This statement is true. A compound is made up of two or more elements chemically bonded together, and it can be decomposed into its constituent elements or simpler compounds by chemical reactions. For example, water (H₂O) can be decomposed into hydrogen (H₂) and oxygen (O₂) through electrolysis, which is a chemical process.
Thus, statement A is false because the composition of a mixture can vary, unlike in a compound, which has a fixed composition.