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:
Let’s break down each option to understand why this is the false statement:
A) Different mixtures of the same two substances must have the same composition.
- This statement is false because mixtures do not have a fixed composition. In mixtures, the proportions of the components can vary. For example, if you mix salt and water, you can have a solution with varying concentrations of salt and water. This flexibility in composition is one of the defining characteristics of mixtures. In contrast, compounds have a fixed, specific ratio of elements.
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 individual components remain distinct and can be physically separated. Sea sand and table salt form a heterogeneous mixture because the sand and salt are visibly distinguishable, and you can separate them through physical means (such as filtering or dissolving the salt in water).
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 where the composition is uniform throughout. When alcohol and water are mixed, they form a solution that has a consistent composition throughout. No distinct layers or components are visible, making it a 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 because a compound is a pure substance formed from two or more elements chemically bonded together. The elements in a compound cannot be separated by physical means but can be decomposed into simpler substances through chemical reactions (e.g., electrolysis of water into hydrogen and oxygen).
Thus, statement A is false because it incorrectly suggests that mixtures have a fixed composition, which is not true. Mixtures can vary in the ratio of components, while compounds have a fixed composition.