Subtest II: Science Study Guide for the CSET Multiple Subjects Test

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General Information

In addition to math, Subtest II of the CSET Multiple Subjects Test contains 26 multiple-choice and two constructed-response questions about science. The areas covered include life, physical, and Earth and space sciences. There will be an onscreen calculator provided for these questions.

You’ll want to go through the following study guide to review your knowledge and assess your readiness for these science questions. Be sure to obtain further study materials if any of this puzzles you.

Physical Sciences

The physical sciences are those that study non-living systems. The main subject of study in the physical sciences is matter and its interactions.

Matter

Matter is defined as everything that occupies space, has an associated mass, and a duration in time. All matter is composed of atoms and can be measured.

Physical Properties

The physical properties of matter are those that can be measured without changing the nature of the substance. To measure them, it is crucial to understand the physical properties of solids, liquids, and gases, such as:

Color—Color is the response of the brain to the stimulation of the eye by light rays with wavelengths roughly between 380 nm and 700 nm that emanate from objects.

Mass—Mass is a physical magnitude that describes the amount of matter that a body has. In the International System of Units (S.I.), it is measured in grams.

Density—Density is the ratio between the mass of an object and its volume. In the S.I., it is measured in $$\frac{kg}{m^3}$$.

Hardness—Hardness is the capacity of a solid substance to resist deformation or abrasion. There are different scales to measure hardness, such as the Mohs, Brinell, and Rockwell scales, with the Mohs scale for rocks and minerals being the most common.

Electrical and thermal conductivity—Generally speaking, conductivity refers to the capacity to transmit something. In the case of electrical conductivity, it refers to the transmission of electrical current; in the case of thermal conductivity, it refers to the capacity to transmit heat.

Changes in Matter

Matter is not static; it can change. It is important to know that matter can undergo physical and chemical changes, which can be described as follows:

Physical changes—Physical changes are those where the chemical nature of the substance doesn’t change. Such changes include dissolving, changing shape, and changes in state such as the evaporation and freezing of water.

Chemical changes—When matter undergoes a chemical change, the atoms in reactants rearrange to form products with new physical and chemical properties. Examples of this are the burning of paper and the rusting of iron.

Conservation of matter laws—In both physical and chemical changes, there are two laws with respect to matter and energy that are always obeyed: the law of conservation of mass and the law of conservation of energy. They state that the initial total amount of mass and energy has to be conserved after matter undergoes any type of change.

Matter Components

Matter is made of atoms. The components of the atom are described below:

Atom—An atom is the smallest stable form of matter. It is composed of protons and neutrons located in a nucleus and of electrons located in electron clouds around the nucleus.

Molecule—A molecule is the combination of two or more atoms. Molecules can be formed by two units of the same atom (like in hydrogen, $$H_2$$), or by different atoms (like in water, $$H_2 O$$). When a molecule is made up of different atoms, as it is with water it is also known as a compound.

Proton—Protons are positively charged particles located in the nucleus of the atom. The number of protons in the nucleus is called the atomic number.

Neutron—Neutrons are neutrally charged particles located in the nucleus of the atom. The sum of the number of protons and neutrons is called the mass number.

Electron—Electrons are negatively charged particles located in electron clouds around the nucleus of the atom. They are described by the electronic configuration of each atom. In a neutral atom, the number of electrons is equal to the number of protons.

Element—An element is a substance formed by atoms with the same atomic number. Atoms are arranged in the periodic table according to their atomic numbers. The most metallic elements, such as sodium and potassium, are located to the left on the periodic table, and the non-metals, such as oxygen and chlorine, are located to the right.

Combining Elements

There are different ways of combining elements and molecules without changing their chemical nature:

Mixture—Mixtures are the combination of two or more substances. They can be homogeneous if the composition is the same throughout the entire sample, and heterogeneous if the composition is variable. To separate them, scientists take advantage of the difference between the physical or chemical properties of the components of the mixture, such as density, boiling point, and magnetism.

Solution—A solution is a type of liquid homogeneous mixture. It can be composed of a solid, liquid, or gaseous solute dissolved into a solvent, and depending on the nature of the solute, it can have different pH levels.

pH level—The pH level is a measure of the acidity of a solution. Acidic solutions, such as lemon juice and coffee, have pH levels between 0 and 7. Neutral solutions have a pH equal to 7 (distilled water), and basic solutions, such as bleach and soapy water, have pH levels between 7 and 14.

Motion and Energy

A body that is in motion has an associated energy, which is defined as the capacity to produce work.

Motion

Motion is a physical parameter that is defined as the change in position of a body in space with respect to time and a reference point.

Describing motion—There are many ways to describe the motion of an object, such as speed, velocity, position, acceleration, and displacement.

The position refers to the coordinates that allow us to locate an object in space at any given time (x). Displacement is the change in position ($$\Delta x = x_2-x_1$$), speed is the ratio between displacement and time ($$s = \frac{\Delta x}{t}$$), velocity is the speed times a vector which describes the direction of the speed, and acceleration is the change in speed with time ($$a = \frac{\Delta s}{t}$$).

Forces—Motion changes when the balance of forces on an object is disrupted. The types of forces that can change the motion of an object include friction, gravity, and magnetism.

Electrical charges—Charged objects may experience changes when exposed to other charges or magnetic fields. Objects can be positively or negatively charged, and objects with the same electrical charge repel each other, while objects with different charges attract each other.

Simple machines—Machines are a set of devices that transform one kind of energy into another to perform work. They change the direction and magnitude of the applied force, allowing people to do more work with less force. An example of this is the lever, which is a long and rigid bar that rotates over a supporting point to overcome a strong resistance with the use of a small force.

Energy

Energy can be manifested in many different ways. That includes chemical, solar, magnetic, sound, nuclear, wind, electrical, electromagnetic, and light energies. The different forms of energy can be converted into each other.

Conservation of energy—In any given process, energy is neither created nor destroyed, but it is converted into other forms of energy. An example of this is the process where the kinetic energy of a power generator is converted into electrical energy.

Velocity and energy relationship—Energy and velocity are related in the form of kinetic energy: $$KE = \frac{1}{2}m \cdot v^2$$.

Heat—Heat is the total energy associated with the movement of the molecules of a substance, while temperature is a measure of the average kinetic energy. For example, a bucket of water can have the same temperature as a small glass of water, but the bucket has more heat because it has more water, and therefore, more total thermal energy.

There are different systems used to measure temperature. The most common ones are degrees Fahrenheit (°F), degrees Celsius (°C), and degrees Kelvin (K). The latter is based on the value of absolute zero and is the unit used in the S.I.

Heat can be transferred by three different mechanisms: conduction (when two bodies are in direct contact), convection (when a body is in contact with a fluid), and radiation (which is independent of the medium and can occur through a vacuum).

Electromagnetic radiation - Electromagnetic radiation is a form of energy emitted by excited atoms in the sun and other sources. It propagates in the form of waves and can interact with matter. Visible light is one form of electromagnetic radiation. Other forms are radio, microwave, infrared, ultraviolet, x-ray, and gamma. Although we cannot see them, they are sometimes referred to as forms of light.

Waves—Waves are a way to transfer energy without transferring matter. Some magnitudes that describe waves are the amplitude (maximum height of the wave), wavelength (the distance between two maximum values), cycle (the complete motion of the wave from the start of the vibration until it comes back to the initial position), period (the time required to perform a cycle), and frequency (the number of cycles per unit time).

Waves have optical properties, such as reflection, a phenomenon that occurs when a wave hits an object that opposes its propagation and is reflected back (this happens with mirrors). Another phenomenon is refraction, when the wave hits a medium with a different propagation speed, changing its direction (this happens when light hits water and changes direction).

Environmental concerns—Humankind needs energy to achieve goals and fulfill needs, but there are certain environmental concerns regarding energy resources. There are renewable energy resources, which are those that can be replenished at a rate that is higher than the consumption rate (e.g., water, wood, solar radiation); and there are non-renewable energy resources, which have a replenishment rate lower than the consumption rate (e.g., fossil fuels). To achieve sustainable development, it is necessary to shift away from non-renewable energy resources and move toward renewable energy.

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