1.
The tiny particles that make up all matter are called
Correct Answer
B. Atoms
Explanation
Atoms are the smallest particles that make up all matter. They are the building blocks of everything around us, including genes, minerals, and cells. Genes are made up of DNA molecules, which in turn are made up of atoms. Minerals are also composed of atoms, arranged in specific patterns. Cells, the basic units of life, are made up of various molecules, which are ultimately made up of atoms. Therefore, atoms are the correct answer as they are the fundamental particles that form all other components of matter.
2.
Which model is used by scientists to determine the properties of elements?
Correct Answer
B. The Periodic Table
Explanation
The Periodic Table is used by scientists to determine the properties of elements. It is a tabular arrangement of chemical elements, organized based on their atomic number, electron configuration, and recurring chemical properties. The table allows scientists to easily identify and compare the properties of different elements, such as their atomic mass, atomic number, symbol, and chemical reactivity. It is an essential tool in the field of chemistry for understanding the behavior and characteristics of elements.
3.
Some common substances and their chemical formulas are listed in the chart below.
Which of these substances are elements?
Correct Answer
D. Helium and oxygen
Explanation
The substances helium and oxygen are elements because they cannot be broken down into simpler substances by chemical means. Hydrochloric acid and carbonic acid are compounds, not elements, because they are composed of more than one type of atom. Carbon dioxide and water are also compounds because they consist of multiple elements chemically bonded together.
4.
Which statement is true about the charges assigned to an electron and a proton?
Correct Answer
C. An electron is negative and a proton is positive
Explanation
An electron is negatively charged because it carries a negative charge. On the other hand, a proton is positively charged because it carries a positive charge.
5.
The elements on the Periodic Table are arranged in order of increasing
Correct Answer
A. Atomic number
Explanation
The elements on the Periodic Table are arranged in order of increasing atomic number. This is because the atomic number represents the number of protons in an atom's nucleus, which determines its chemical properties and its position on the Periodic Table. The atomic number also determines the number of electrons in a neutral atom, making it a fundamental property of an element. Therefore, arranging the elements in order of increasing atomic number allows for a systematic organization and classification of the elements based on their atomic properties.
6.
The diagram below shows the geometric structure of a molecule of water (H2O).
What do the symbols and represent in the model?
Correct Answer
D. Atoms
Explanation
The symbols "H" and "O" represent atoms in the model of the water molecule. In the molecule of water (H2O), "H" represents hydrogen atoms and "O" represents an oxygen atom.
7.
The table below shows the chemical symbols for some common elements.
Based on the information in the table, which of the four substance below is a compound?
Correct Answer
A. CO
Explanation
The chemical symbol CO represents the compound carbon monoxide, which consists of one carbon atom (C) and one oxygen atom (O). Therefore, CO is a compound. Si, Fe, and He are all chemical symbols for elements (silicon, iron, and helium, respectively), not compounds.
8.
Which diagram best represents molecules of matter in the solid phase?
Correct Answer
B. 2
Explanation
Diagram 2 represents molecules of matter in the solid phase because the molecules are closely packed together in a regular pattern. In a solid, the molecules are held together by strong intermolecular forces, causing them to vibrate in fixed positions. Diagram 2 accurately depicts this arrangement of molecules in a solid state. Diagram 1 shows molecules that are too spread out, indicating a gas phase. Diagram 3 shows molecules that are not arranged in a regular pattern, suggesting a liquid phase. Diagram 4 shows molecules that are too far apart and not interacting, indicating a gas phase. Therefore, diagram 2 is the best representation of molecules of matter in the solid phase.
9.
Which substance is usually found in nature as a liquid, solid, and gas?
Correct Answer
A. Water
Explanation
Water is usually found in nature as a liquid, solid, and gas. At normal temperatures and pressures, water exists as a liquid, which is the most common form. At lower temperatures, water can freeze and become a solid, such as ice. At higher temperatures, water can evaporate and become a gas, such as water vapor. This ability of water to exist in all three states of matter is due to its unique molecular structure and the hydrogen bonding between its molecules.
10.
A wet shirt is put on a clothesline to dry on a sunny day. The shirt dries because water molecules
Correct Answer
B. Gain heat energy and evaporate
Explanation
On a sunny day, the shirt is exposed to heat from the sun. This heat energy is absorbed by the water molecules present in the wet shirt. As a result, the water molecules gain enough energy to overcome the attractive forces between them and escape into the air in the form of water vapor. This process is known as evaporation. Therefore, the correct answer is "gain heat energy and evaporate."
11.
Which graph correctly shows the effect of heat energy on the motion of molecules of matter?
Correct Answer
C. 3
Explanation
Graph 3 correctly shows the effect of heat energy on the motion of molecules of matter. As heat energy is applied, the molecules gain kinetic energy and their motion increases. The graph shows an increase in the speed or kinetic energy of the molecules as the temperature or heat energy increases.
12.
Which observation would be evidence that the water is undergoing a phase change?
Correct Answer
D. The water level in the glass of water decreases.
Explanation
When the water level in the glass of water decreases, it indicates that the water is undergoing a phase change, specifically the phase change from liquid to gas, known as evaporation.
13.
How is heat energy transferred within the liquid water in the pond?
Correct Answer
B. Convection currents
Explanation
Heat energy is transferred within the liquid water in the pond through convection currents. Convection is the process of heat transfer through the movement of a fluid, in this case, water. As the water in the pond is heated, it becomes less dense and rises, while the cooler water sinks. This creates a circular flow of water, known as convection currents, which allows the heat energy to be distributed throughout the pond.
14.
The four diagrams below model the results of mixing atoms of different substances. Each atom is represented by a different symbol. Which diagram correctly models a chemical change?
Correct Answer
B. 2
15.
The diagram below shows a boy observing a fish located at position B below the surface of the water. The boy sees the fish at position A.
The apparent position of the fish is different from the actual position of the fish. What has happened to the light passing through the water to cause this difference?
Correct Answer
D. Refraction
Explanation
When light passes from one medium to another, such as from air to water, it changes speed and direction. This phenomenon is known as refraction. In this case, as light travels from water to air, it bends or changes direction, causing the apparent position of the fish to be different from its actual position. This is because the light rays coming from the fish are refracted or bent at the water-air interface, creating the illusion that the fish is at a different location.
16.
Hydrochloric acid is added to a beaker containing a piece of zinc. As a result, zinc chloride is formed and hydrogen gas is released. This is an example of
Correct Answer
A. A chemical reaction
Explanation
When hydrochloric acid is added to zinc, a chemical reaction occurs. This is because the hydrochloric acid reacts with the zinc to form zinc chloride and hydrogen gas. This reaction involves the breaking and forming of chemical bonds, resulting in the formation of new substances with different properties than the reactants. Therefore, this is an example of a chemical reaction.
17.
Which form of energy is needed to change water from a liquid to a gas?
Correct Answer
A. Heat
Explanation
When water changes from a liquid to a gas, it undergoes a process called evaporation. This requires energy input to break the intermolecular forces between water molecules and convert them into a gaseous state. Heat is the form of energy that is needed for this phase change to occur, as it provides the necessary energy to increase the kinetic energy of the water molecules and overcome the attractive forces holding them together.
18.
A student crumples up a sheet of paper. Which property of the paper has changed?
Correct Answer
D. Shape
Explanation
The correct answer is shape. When the student crumples up the sheet of paper, its shape changes from flat to crumpled. The other properties of the paper, such as its color, mass, and state (which is typically solid), remain the same.
19.
Sound will not travel in a
Correct Answer
D. Vacuum
Explanation
Sound requires a medium to travel through, such as a solid, liquid, or gas, because it relies on the vibration of particles. In a vacuum, there are no particles present to vibrate and transmit the sound waves. Therefore, sound cannot travel in a vacuum.
20.
Which statement best describes the property of light waves illustrated in the diagram below?
Correct Answer
C. Light waves are refracted by some materials
Explanation
The diagram shows a light wave passing through a material and changing direction. This phenomenon is known as refraction, which occurs when light waves travel from one medium to another with a different refractive index. Therefore, the statement "Light waves are refracted by some materials" best describes the property of light waves illustrated in the diagram.
21.
Which diagram represents electromagnetic energy with the shortest wavelength?
Correct Answer
B. B
Explanation
Diagram B represents electromagnetic energy with the shortest wavelength because the waves in this diagram are tightly packed together, indicating a high frequency and short wavelength. The other diagrams (A, C, and D) have waves that are more spread out, indicating lower frequencies and longer wavelengths.
22.
The picture below shows a ringing bell inside a vacuum jar.
As air is pumped from the vacuum jar, the sound level of the ringing bell will decrease until it can no longer be heard. This happens because air must be present in the jar in order for
Correct Answer
A. Sound to be transferred
Explanation
The correct answer is "sound to be transferred". Sound waves need a medium, such as air, to travel through. In a vacuum jar where air is pumped out, there is no medium for the sound waves to travel through, resulting in the sound level of the ringing bell decreasing until it can no longer be heard.
23.
A common characteristic of sound waves is that they
Correct Answer
A. Are created by vibrations
Explanation
Sound waves are created by vibrations. When an object vibrates, it causes the surrounding air particles to vibrate as well, creating a disturbance that propagates as a sound wave. This is a fundamental characteristic of sound waves and is essential for the transmission of sound from a source to a receiver.
24.
When a person speaks into a telephone, sound energy is changed mostly into which form of energy?
Correct Answer
C. Electrical
Explanation
When a person speaks into a telephone, the sound energy is converted mostly into electrical energy. This is because the sound waves created by the person's voice cause vibrations in the microphone of the telephone, which then converts these vibrations into electrical signals. These electrical signals are then transmitted through the telephone wires and converted back into sound waves by the receiver, allowing the person on the other end to hear the voice.
25.
Chemical and physical changes are a part of everyday life. What are 2 ways that humans use chemical changes and physical changes to their advantage? (Use RAFFT or any short response technique to answer this quesiton in the space provided)