Chapter 2.1 and 2.2 Test Review

What is the basic unit of matter?

• Molecule

• Atom

• Element

• Cell

Answer explanation

The basic unit of matter is the atom, which consists of protons, neutrons, and electrons. Molecules are made up of atoms, elements are pure substances of one type of atom, and cells are the basic units of life, not matter.

Which subatomic particle is positively charged?

• Proton

• Neutron

• Electron

• Molecule

Answer explanation

The proton is the subatomic particle that carries a positive charge, distinguishing it from neutrons, which are neutral, and electrons, which are negatively charged. Molecules are made up of atoms and do not represent a single subatomic particle.

What term refers to atoms of the same element with different numbers of neutrons?

• Ions

• Isotopes

• Compounds

• Molecules

Answer explanation

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. This distinguishes them from ions, compounds, and molecules.

What is the name of the center of an atom, where protons and neutrons are located?

• Shell

• Orbital

• Nucleus

• Core

Answer explanation

The center of an atom, where protons and neutrons are located, is called the nucleus. The other options, such as shell and orbital, refer to regions where electrons are found, not the core of the atom.

What type of bond forms when atoms share electrons?

• Ionic bond

• Covalent bond

• Hydrogen bond

• Polar bond

Answer explanation

A covalent bond forms when two atoms share electrons to achieve stability. This type of bond contrasts with ionic bonds, where electrons are transferred, and hydrogen bonds, which are weaker interactions.

What does the chemical formula H₂O represent?

• Salt

• Water

• Hydrogen peroxide

• Oxygen

Answer explanation

The chemical formula H₂O represents water, which consists of two hydrogen atoms bonded to one oxygen atom. This distinguishes it from other compounds like salt (NaCl) and hydrogen peroxide (H₂O₂).

Tags

NGSS.MS-PS1-1

What property of water allows it to stick to other substances, like glass?

• Cohesion

• Adhesion

• Surface tension

• Polarity

Answer explanation

Adhesion is the property of water that allows it to stick to other substances, such as glass. This occurs because water molecules are attracted to the molecules of the glass, enabling them to adhere together.

What is the pH of pure water?

• 0

• 5

• 7

• 14

Answer explanation

The pH of pure water is 7, which is considered neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity. Therefore, the correct answer is 7.

Which subatomic particle orbits the nucleus of an atom?

• Proton

• Electron

• Neutron

• Ion

Answer explanation

The electron is the subatomic particle that orbits the nucleus of an atom. Protons and neutrons are found in the nucleus, while ions are charged particles that can be formed from atoms.

What is a solution?

• A chemical compound

• A material with unevenly distributed components

• A mixture where components are evenly distributed

• A suspension of particles

Answer explanation

A solution is defined as a mixture where components are evenly distributed at the molecular level, resulting in a homogeneous phase. This distinguishes it from suspensions or uneven mixtures.