Give the classification of matter when two substances exist with two phases present.
a) heterogeneous mixture
b) homogeneous mixture
c) compound
d) element
The correct answer and explanation is :
The correct answer is a) heterogeneous mixture.
Explanation:
Matter can be classified based on its composition and the number of phases it exhibits. A “phase” in this context refers to a distinct and physically separate part of a system with uniform properties. For example, a solid, liquid, or gas is considered a single phase, and when these different phases are combined, we observe how they interact.
In a heterogeneous mixture, two or more substances are combined, and these substances are not uniformly distributed. They exist in separate phases, meaning that you can visually distinguish one part of the mixture from another. This is characteristic of mixtures like oil and water, where oil forms one phase (liquid) and water forms another phase (liquid), but they do not dissolve into each other. Similarly, a salad with different components (lettuce, tomatoes, dressing) represents a heterogeneous mixture because the individual components can be physically separated.
On the other hand, in a homogeneous mixture (option b), the substances are uniformly distributed, and the mixture appears as a single phase. An example would be salt dissolved in water, where you cannot distinguish the individual components (salt and water) because the salt is dissolved uniformly in the water, forming a single phase.
A compound (option c) is a substance that consists of two or more elements chemically combined in fixed proportions. Compounds are uniform throughout (i.e., they are homogeneous), and the atoms are bonded together in specific ways. Water (H₂O) is a compound, but it does not have two phases unless it undergoes a phase change (such as freezing or boiling).
An element (option d) is a pure substance made up of only one type of atom. It cannot be separated into simpler substances by chemical means and exists as a single phase under standard conditions. Examples include hydrogen, oxygen, or gold.
Thus, when two substances exist with two distinct phases, they form a heterogeneous mixture, as the phases are physically separate and distinguishable.