Chem Unit 1 Review

Wood burning is an example of _______

• physical intensive property

• physical extensive property

• chemical change

• Physical change

Answer explanation

The process of wood burning is a chemical change because it involves a reaction that transforms the substance wood into new substances, such as ash, smoke, and gases like carbon dioxide and water vapor. This process is not reversible, which is a key characteristic of chemical changes.

Crumpling paper is an example of 

• physical change

• chemical change

• physical property

• chemical property

Answer explanation

Crumpling paper is an example of a physical change because there is a change in the form of the paper, but no new substances are created. The paper's chemical composition remains the same before and after the action. Hence, it's not a chemical change or property.

All of these are examples of chemical properties except...

• Flammability

• Combusting

• Fizzing

• Boiling Point

Answer explanation

The question asks for the property which is not a chemical property among the given options. Flammability, Combusting, and Fizzing all indicate the substance's ability to undergo a certain chemical reaction. However, the Boiling Point is a physical property because it describes a phase change, not a chemical change. Therefore, Boiling Point is the correct answer.

If it has mass and takes up space it can be considered

• Matter

• Physical Property

• Chemical Property

• Density

Answer explanation

The question asks what can be considered if it has mass and takes up space. The answer is 'Matter'. This is because, in science, anything that has mass and takes up space is referred to as matter. The other options like 'Physical Property', 'Chemical Property', and 'Density' are attributes or properties of matter, not matter itself. Therefore, 'Matter' is the correct option.

What is a kind of matter that cannot be broken down into any other kind of substance?

• Elements

• Mixtures

• Compounds

• Density

Answer explanation

In the question, we are asked to identify a kind of matter that can't be broken down further. This perfectly describes an Element. Elements are pure substances that cannot be broken down into other types of substances by any physical or chemical means. Therefore, the correct answer is 'Elements'. Mixtures, Compounds, and Density do not meet this definition.

What is a mixture that has no visible differences in composition?

• Element

• Compound

• Heterogeneous Mixture

• Homogeneous Mixture

Answer explanation

A Homogeneous Mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties. This means there are no visible differences in the mixture. On the contrary, elements, compounds, and heterogeneous mixtures can show visible differences in their composition.

What is the atomic number?

• the number of protons in the nucleus

• the number of protons and neutrons in the nucleus

• the number of neutrons in the nucleus

• the number of protons in the energy levels

Answer explanation

The atomic number refers to the number of protons in the nucleus of an atom. Therefore, the correct answer to the question is 'the number of protons in the nucleus'. The other options, including the number of protons and neutrons, neutrons alone, or protons in the energy levels, are incorrect as they do not define the atomic number.

What is the mass number?

• the number of protons in the nucleus

• the number of protons and neutrons in the nucleus

• the number of neutrons in the nucleus

• the number of protons and electrons in the atom

Answer explanation

The mass number, as per the question, is the total number of protons and neutrons in the nucleus of an atom. This rules out the other options which only mention either protons or neutrons, or include electrons which are not part of the nucleus.

What is the atomic number of this atom?

• 1

• 3

• 4

• 7

Answer explanation

The atomic number represents the number of protons in an atom's nucleus. Here, the correct answer is 3, indicating that this atom has 3 protons, and hence, its atomic number is 3.

Most of the mass in an atom is made up of _____________________?

• protons and electrons

• protons and neutrons

• neutrons and electrons

• electrons and quarks

Answer explanation

The answer to the question 'Most of the mass in an atom is made up of what?' is 'protons and neutrons'. This is because the nucleus of an atom, which is where most of the mass of an atom is located, is made up of both protons and neutrons. Electrons, on the other hand, have much less mass than protons and neutrons, while quarks are components of protons and neutrons