Question

1. which of the following is an example of a heterogeneous mixture?

a) salt dissolved in water
b) air
c) oil mixed with water
d) sugar dissolved in water

1. salt dissolves in water. what is salt considered in this solution?

a) solvent
b) solute
c) suspension
d) element

1. which of the following mixtures can be separated by physical means (like filtration)?

a) saltwater
b) oil and water mixture
c) sugar dissolved in water
d) oxygen gas

1. what type of mixture is saltwater?

a) homogeneous mixture
b) heterogeneous mixture
c) compound
d) element

1. which of these substances is insoluble in water?

a) sugar
b) salt
c) oil
d) vinegar

1. which of the following best describes a compound?

a) a substance made of only one type of atom
b) a substance made of two or more elements chemically combined
c) a mixture where substances are physically combined but can be separated
d) a mixture that looks the same throughout

1. which statement is true about pure substances compared to mixtures?

a) pure substances can be separated easily by physical means
b) mixtures have fixed composition
c) pure substances have fixed composition and properties
d) mixtures are made of only one type of atom

Explanation:

• Question 4: A heterogeneous mixture has visibly different parts. Oil and water do not mix uniformly, so it is a heterogeneous mixture. Salt dissolved in water, air, and sugar dissolved in water are homogeneous mixtures (uniform throughout).
• Question 5: In a solution, the solute is the substance that is dissolved. Here, salt is dissolved in water, so salt is the solute. The solvent is the substance that does the dissolving (water in this case). A suspension is a type of mixture where particles are dispersed but not dissolved. An element is a pure substance made of only one type of atom.
• Question 6: Oil and water mixture can be separated by physical means like decantation (since they form two layers). Saltwater and sugar dissolved in water are solutions and cannot be separated by filtration. Oxygen gas is a pure substance, not a mixture.
• Question 7: Saltwater is a homogeneous mixture because the salt is uniformly dissolved in water. A heterogeneous mixture has visibly different parts. A compound is a pure substance made of two or more elements chemically combined. An element is a pure substance made of only one type of atom.
• Question 8: Oil is insoluble in water. Sugar and salt are soluble in water (they dissolve to form solutions). Vinegar (acetic acid solution) is also soluble in water.
• Question 9: A compound is defined as a substance made of two or more elements chemically combined. A substance made of only one type of atom is an element. A mixture where substances are physically combined but can be separated is a mixture (not a compound). A mixture that looks the same throughout is a homogeneous mixture.
• Question 10: Pure substances have fixed composition and properties. They cannot be separated easily by physical means (unlike mixtures). Mixtures do not have a fixed composition. A substance made of only one type of atom is an element (a type of pure substance), not a mixture.

Answer:

1. C. Oil mixed with water
2. B. Solute
3. B. Oil and water mixture
4. A. Homogeneous mixture
5. C. Oil
6. B. A substance made of two or more elements chemically combined
7. C. Pure substances have fixed composition and properties