Can You Pass This Basic Chemistry Exam?

Burning wood is an example of a chemical change because it involves a chemical reaction. When wood burns, it undergoes a combustion reaction that releases heat and light energy, and produces new substances such as carbon dioxide, water vapor, and ash. This chemical reaction changes the composition and properties of the wood, making it a clear example of a chemical change.

Atoms are the smallest particles that make up all elements. Compounds are made up of two or more different types of atoms bonded together. Mixtures are combinations of different substances that are physically combined but not chemically bonded. Molecules are formed when two or more atoms are chemically bonded together. Therefore, atoms are the correct answer as they are the building blocks of all elements.

Soil, a salad, and sugar water are all examples of mixtures because they consist of two or more substances that are physically combined but can be separated by physical means. In the case of soil, it is a mixture of minerals, organic matter, water, and air. A salad is a mixture of various vegetables, fruits, and sometimes proteins or dressings. Sugar water is a mixture of water and sugar molecules. Therefore, all of these examples exhibit the characteristics of mixtures.

Elements are substances that cannot be broken down chemically into other substances. They are the simplest form of matter and consist of only one type of atom. Compounds, mixtures, and solutions, on the other hand, are made up of multiple elements or substances that can be chemically or physically separated into their individual components. Therefore, the correct answer is elements.

Salt dissolving in a glass of water is not an example of a chemical change because it is a physical change. In this process, the salt molecules are simply being dispersed and separated in the water, but their chemical composition remains the same. No new substances are formed, and the salt can easily be recovered by evaporating the water.

A gas that easily catches fire is exhibiting a characteristic that is related to its chemical behavior rather than its physical state or composition. It indicates a tendency for the gas to undergo a chemical reaction and ignite when exposed to a flame or spark. Therefore, describing a gas that easily catches fire is describing a chemical property.

The statement "Atoms of different elements are the same" is false. Atoms of different elements have different properties and characteristics. Each element is defined by the number of protons in its nucleus, which determines its atomic number and unique identity. Therefore, atoms of different elements are not the same and can be distinguished based on their atomic structure and properties.

When heating a liquid and measuring its boiling temperature, you are observing a physical property. This is because the boiling temperature is a characteristic of the substance itself and does not involve any changes in its chemical composition or atomic structure. Physical properties can be measured or observed without altering the substance's identity, and boiling temperature is one such property that helps identify and classify different substances.

Dissolving salt in water is an example of a physical change because it only involves a change in the physical state of the substances involved. When salt is added to water, it breaks down into individual ions and disperses evenly throughout the water. The chemical composition of both the salt and the water remains unchanged, and the salt can be easily separated from the water through evaporation. Therefore, dissolving salt in water is a physical change rather than a chemical reaction.

Table sugar and table salt are examples of pure substances because they are both compounds that consist of a single type of molecule. In the case of table sugar, it is made up of sucrose molecules, while table salt is composed of sodium chloride molecules. Pure substances have a fixed composition and distinct chemical properties, which is true for both table sugar and table salt.