1.
Give me one example of an element, a compound, a homogeneous mixture, and a heterogeneous mixture.
2.
Anything that has mass and takes up space is _________.
Correct Answer
A. Matter
Explanation
The question is asking for something that has mass and takes up space. Matter is the term used to describe anything that has mass and occupies space. Therefore, matter is the correct answer.
3.
A sample of gold has a mass of 15.7 g and displaces 0.81 cm3 of water in a graduated cylinder. What is the density of gold? Density = mass/volume
Correct Answer
D. 19.3 g/cm3
Explanation
The density of a substance is calculated by dividing its mass by its volume. In this case, the mass of the gold sample is given as 15.7 g and the volume of water displaced by the gold sample is given as 0.81 cm3. By dividing the mass (15.7 g) by the volume (0.81 cm3), we can calculate the density of gold. The result is 19.3 g/cm3, which is the correct answer.
4.
Which of the following numbers is equal to 2.70 x 10-4?
Correct Answer
A. 0.00027
Explanation
The correct answer is 0.00027 because when we multiply 2.70 by 10 raised to the power of -4, we move the decimal point 4 places to the left, resulting in a value of 0.000027.
5.
A characteristic that can be observed or measured without changing the sample's composition is ________________.
Correct Answer
B. A pHysical property
Explanation
A physical property is a characteristic of a substance that can be observed or measured without changing the composition of the sample. This means that even if we measure or observe the physical property, the substance will still remain the same. Examples of physical properties include color, density, melting point, boiling point, and conductivity.
6.
When one substance changes identity, it exhibits a(n) __________.
Correct Answer
A. Chemical property
Explanation
When one substance changes identity, it exhibits a chemical property. Chemical properties are characteristics of a substance that can only be observed or measured when a chemical change occurs. These properties describe how a substance reacts with other substances, such as its ability to burn, rust, or decompose. In contrast, physical properties describe the characteristics of a substance that can be observed or measured without changing its identity, such as color, density, or melting point. Extensive properties depend on the amount of substance present, while intensive properties do not.
7.
Which of the following is a pure substance?
Correct Answer
D. Steam
Explanation
Steam is a pure substance because it consists of only one type of molecule, which is water vapor. It does not contain any impurities or other substances mixed in it. Unlike soda, gun powder, and sugar water, which are all mixtures of different substances, steam is a single component and therefore qualifies as a pure substance.
8.
Which of these is not a homogeneous mixture?
Correct Answer
C. Oil and vinegar salad dressing
Explanation
Oil and vinegar salad dressing is not a homogeneous mixture because it is a suspension of oil droplets in vinegar. Homogeneous mixtures have uniform composition and properties throughout, whereas in the case of salad dressing, the oil and vinegar do not fully mix and separate over time. On the other hand, sugar dissolved in water, oxygen and nitrogen gases in the air, and a silver mercury amalgam used to fill a tooth cavity are all examples of homogeneous mixtures as they have uniform composition and properties.
9.
Which of the following is a compound?
Correct Answer
A. Water
Explanation
Water is not a compound because it consists of only one type of atom, which is oxygen and hydrogen. A compound is a substance formed by the chemical combination of two or more elements in definite proportions. In the case of water, it is a molecule composed of two hydrogen atoms and one oxygen atom, making it a simple molecule or a pure substance.
10.
Classify as a physical or a chemical property.
Iron is more dense than aluminum.
Correct Answer
B. pHysical
Explanation
The given statement "Iron is more dense than aluminum" refers to a comparison of the densities of iron and aluminum. Density is a physical property of a substance that describes the mass per unit volume. In this case, the statement is comparing the densities of two different elements, iron and aluminum. Since density is a characteristic that can be measured and observed without changing the chemical composition of the substances, it is considered a physical property. Therefore, the correct answer is physical.
11.
Classify as a physical or a chemical property.
Oil and water do not mix.
Correct Answer
B. pHysical
Explanation
The fact that oil and water do not mix is classified as a physical property. This is because it is a characteristic that can be observed without changing the chemical composition of the substances. It is a property that describes the behavior or interaction of the substances, rather than a change in their chemical structure.
12.
Identify each physical property as extensive or intensive.
melting point
Correct Answer
A. Intensive
Explanation
The melting point of a substance is an intensive physical property. Intensive properties do not depend on the amount of substance present and remain constant regardless of the quantity. In the case of melting point, it is the temperature at which a substance changes from a solid to a liquid state, and this temperature does not change with the amount of substance being melted.
13.
Identify each physical property as extensive or intensive.
mass
Correct Answer
B. Extensive
Explanation
Mass is an extensive physical property because it depends on the amount of matter present in an object. The more matter an object has, the greater its mass will be. Extensive properties are additive, meaning they can be added or subtracted when objects are combined or separated. In contrast, intensive properties, such as density or temperature, do not depend on the amount of matter and remain constant regardless of the quantity of the substance.
14.
Identify each physical property as extensive or intensive.
density
Correct Answer
A. Intensive
Explanation
Density is an intensive physical property because it does not depend on the amount or size of the substance being measured. It remains the same regardless of the quantity of the substance.
15.
Classify as a physical change or a chemical change.
water freezing and forming ice
Correct Answer
A. pHysical
Explanation
Water freezing and forming ice is classified as a physical change because it involves a change in the state of matter from a liquid to a solid, but the chemical composition of water remains the same. In this process, the water molecules slow down and come closer together, forming a solid structure. The freezing of water can be reversed by melting the ice, demonstrating that no new substances are formed during this change.
16.
Classify as a physical change or a chemical change.
leaves changing colors in the fall
Correct Answer
B. Chemical
Explanation
The process of leaves changing colors in the fall is a chemical change. This is because the pigments in the leaves undergo a chemical reaction, breaking down and changing their composition, resulting in the vibrant colors that we see. It is not a physical change because the change in color is not reversible and involves a transformation at the molecular level.
17.
Two items that must be worn during any laboratory experiment are ___________.
Correct Answer
A. Safety goggles and a lab apron
Explanation
During a laboratory experiment, it is essential to wear safety goggles to protect the eyes from any potential hazards such as chemicals or flying objects. Additionally, a lab apron should be worn to protect the body and clothing from spills or splashes of chemicals. Therefore, the correct answer is safety goggles and a lab apron.
18.
When a laboratory session ends, you must always ___________.
Correct Answer
A. Wash your hands
Explanation
After a laboratory session, it is important to wash your hands to maintain proper hygiene and prevent the spread of any chemicals or contaminants that may have been encountered during the session. Washing hands helps to remove any potential harmful substances and reduce the risk of contamination or infection.
19.
Use the conversion factor above to find the meters in 2.7 x 103 kilometers. 1 km = 1000 m
Correct Answer
D. 2.7 x 10^6 m
Explanation
The given conversion factor states that 1 kilometer is equal to 1000 meters. To find the number of meters in 2.7 x 10^3 kilometers, we can multiply 2.7 x 10^3 by the conversion factor. This gives us 2.7 x 10^3 km * 1000 m/km = 2.7 x 10^6 m. Therefore, the answer is 2.7 x 10^6 m.
20.
Classify the following as a physical or a chemical change. Iron and oxygen form rust
Correct Answer
A. Chemical
Explanation
The formation of rust when iron and oxygen combine is considered a chemical change. This is because the reaction between iron and oxygen results in the formation of a new substance, rust. In a chemical change, the composition of the substances involved is altered, and new substances are formed with different properties. In this case, the iron reacts with oxygen to form iron oxide, which is the chemical name for rust.