1.
Which list shows mixtures in which the particles dispersed in water are increasing in size?
Correct Answer
B. Solution, colloid, suspension
Explanation
The correct answer is solution, colloid, suspension. This is because in a solution, the particles are evenly dispersed and cannot be seen with the naked eye. In a colloid, the particles are larger than those in a solution and can scatter light, making the mixture appear cloudy or opaque. In a suspension, the particles are even larger and can settle at the bottom over time, causing the mixture to become heterogeneous. Therefore, the particles dispersed in water are increasing in size from solution to colloid to suspension.
2.
Which of the following descriptions is correct?
Correct Answer
B. A colloid is a 'cloudy' mixture containing particles which will not easily settle out when the colloid is left standing
Explanation
A colloid is a 'cloudy' mixture containing particles which will not easily settle out when the colloid is left standing. This means that the particles in a colloid are dispersed evenly throughout the mixture and do not settle to the bottom over time. This is different from a suspension, where the particles will eventually settle out if the suspension is left undisturbed. A solution, on the other hand, is a mixture where the solute is completely dissolved in the solvent. Finally, a mixture can be separated by physical methods, not just chemical methods.
3.
Which of the following would not be described as a colloid?
Correct Answer
A. Saltwater
Explanation
Saltwater would not be described as a colloid because it is a homogeneous mixture where the solute (salt) is completely dissolved in the solvent (water), resulting in a clear and transparent solution. In a colloid, the particles of the solute would be dispersed throughout the solvent, creating a cloudy or opaque appearance. Foam, fog, and smoke are examples of colloids as they consist of small particles or droplets dispersed in a gas or liquid, causing them to be visibly cloudy or opaque.
4.
A mixture of iron filings and copper filings could best be separated by:
Correct Answer
C. Magnetic separation
Explanation
A mixture of iron filings and copper filings can be best separated by magnetic separation. This is because iron filings are magnetic, while copper filings are not. By using a magnet, the iron filings can be attracted and separated from the mixture, leaving behind the copper filings. This method takes advantage of the different physical properties of the two substances to achieve separation.
5.
When coffee powder is dissolved in hot water, the water is:
Correct Answer
B. The solvent
Explanation
In this scenario, the coffee powder is being dissolved in the hot water. The substance that is doing the dissolving is known as the solvent, while the substance that is being dissolved is called the solute. Therefore, in this case, the hot water is acting as the solvent, while the coffee powder is the solute.
6.
When the coffee powder is dissolved in hot water, the coffee is:
Correct Answer
A. The solute
Explanation
When coffee powder is dissolved in hot water, the coffee powder is the solute. In a solution, the solute is the substance that is being dissolved. In this case, the coffee powder is being dissolved in the hot water, making it the solute. The solvent, on the other hand, is the substance that does the dissolving, which in this case is the hot water. The solution is the resulting mixture of the solute (coffee powder) and the solvent (hot water).
7.
When the coffee powder is dissolved in hot water, the mixture of the two is
Correct Answer
C. A solution
Explanation
When the coffee powder is dissolved in hot water, it forms a homogeneous mixture where the coffee particles are evenly distributed throughout the water. This mixture is called a solution, where the coffee powder acts as the solute and the hot water acts as the solvent. The solute is the substance that gets dissolved, while the solvent is the substance that does the dissolving. Therefore, the correct answer is a solution.
8.
When a mixture is made no new substances are formed.
Correct Answer
A. True
Explanation
When a mixture is made, it means that different substances are combined together without any chemical reaction taking place. In other words, the original substances in the mixture retain their individual properties and no new substances with different properties are formed. Therefore, the statement "When a mixture is made no new substances are formed" is true.
9.
In a solution, the solvent is always water.
Correct Answer
B. False
Explanation
The statement is false because in a solution, the solvent is not always water. While water is a commonly used solvent, there are many other solvents that can be used depending on the nature of the solute. Different solvents have different properties and can dissolve different solutes, so water is not the only option for a solvent in a solution.
10.
Select three examples of colloids.
Correct Answer(s)
B. Shaving cream
C. Campfire smoke
F. Murky pond water
Explanation
The three examples of colloids mentioned in the answer are shaving cream, campfire smoke, and murky pond water. Colloids are mixtures where one substance is dispersed evenly in another substance, creating a stable suspension. Shaving cream is a colloid because it consists of tiny air bubbles dispersed in a liquid. Campfire smoke is also a colloid as it contains small particles of soot and other substances dispersed in the air. Murky pond water is a colloid because it contains suspended particles such as algae, sediment, and other organic matter.
11.
Select three examples of a solution.
Correct Answer(s)
A. Lemonade
C. Salt water
E. A cup of instant coffee
Explanation
The correct answer is Lemonade, Salt water, and a cup of instant coffee. These examples all represent solutions because they involve a solute (lemonade mix, salt, coffee) being dissolved in a solvent (water). In lemonade, the solute is the lemonade mix dissolved in water; in salt water, the solute is salt dissolved in water; and in a cup of instant coffee, the solute is coffee granules dissolved in water. In all three cases, the solute particles become evenly distributed throughout the solvent, creating a homogeneous mixture.
12.
Select three examples of a suspension.
Correct Answer(s)
A. Sand and water
D. Engine oil and metal particles
E. A snow globe with glitter pieces in liquid that you shake
Explanation
The three examples of suspension are sand and water, engine oil and metal particles, and a snow globe with glitter pieces in liquid that you shake. In a suspension, solid particles are dispersed in a liquid or gas, but they do not dissolve and eventually settle down. In the case of sand and water, the sand particles are suspended in the water but will eventually settle at the bottom. Similarly, in engine oil and metal particles, the metal particles are suspended in the oil. In the snow globe example, the glitter pieces are suspended in the liquid, creating a visually appealing effect when shaken.