1.
Which of the following is not included in physical science?
Correct Answer
D. Zoology
Explanation
Zoology is not included in physical science because physical science primarily focuses on the study of non-living matter and energy, whereas zoology is the branch of biology that specifically deals with the study of animals. Physical science encompasses physics, chemistry, and astronomy, all of which primarily study the fundamental principles and properties of matter and energy. Zoology, on the other hand, is concerned with the study of living organisms, their behavior, and their interactions with their environment.
2.
What science deals most with energy and forces?
Correct Answer
B. pHysics
Explanation
Physics is the branch of science that deals most with energy and forces. It studies the fundamental principles of nature, including the behavior of matter and energy, and the interactions between them. Physics explores various forms of energy, such as mechanical, thermal, electromagnetic, and nuclear energy, and investigates the forces that govern their behavior. It aims to understand the fundamental laws that govern the universe and how energy and forces shape the world around us. Biology, botany, and agriculture, on the other hand, focus more on living organisms and their interactions with the environment rather than energy and forces.
3.
Using superconductors to build computers is an example of
Correct Answer
A. Technology.
Explanation
Using superconductors to build computers is an example of technology because it involves the practical application of scientific knowledge to create a useful and functional device. Superconductors are materials that can conduct electricity with zero resistance at very low temperatures, and utilizing this property in computer technology can significantly enhance their performance and efficiency. This application of superconductors in computer technology falls under the realm of technology, which focuses on the practical implementation and development of scientific discoveries for practical purposes.
4.
A balance is a scientific tool used to measure
Correct Answer
D. Mass.
Explanation
A balance is a scientific tool used to measure mass. It works by comparing an unknown mass to a known mass, allowing for accurate measurement. Temperature is typically measured using a thermometer, time is measured using a clock or stopwatch, and volume is measured using tools such as graduated cylinders or beakers. However, a balance is specifically designed to measure mass by comparing the gravitational force exerted on an object. Therefore, the correct answer is mass.
5.
Which of the following units is an SI base unit?
Correct Answer
B. Kilogram
Explanation
Among the options provided, the SI (International System of Units) base unit is the "kilogram." The kilogram is one of the seven base SI units, and it is the base unit for measuring mass. The other units listed are derived units or are not part of the SI base units. The "centimeter" is not an SI base unit but a derived unit for length, with the base SI unit for length being the meter (m). The "cubic meter" is not a base unit but a derived unit for volume. It is derived from the base unit of length (meter) and represents the volume of a cube with sides of one meter. The "liter" is not an SI base unit, although it is a commonly used unit for measuring volume. The SI unit for volume is the cubic meter (m³).
6.
The composition of the mixture of gases that makes up our air is best represented on what kind of graph?
Correct Answer
D. Pie chart
Explanation
A pie chart is the best representation for the composition of the mixture of gases in our air because it visually displays the proportions of different gases as slices of a pie. Each slice represents a specific gas, and the size of the slice corresponds to the percentage or proportion of that gas in the mixture. This allows for an easy comparison of the different gases and their relative amounts in the air. A line graph shows the relationship between variables over a continuous scale, a variable graph is not a commonly used term, and a bar graph is more suitable for comparing discrete categories or quantities.
7.
In a controlled experiment,
Correct Answer
D. One variable is changed while all others remain fixed.
Explanation
In a controlled experiment, one variable is changed while all others remain fixed. This allows researchers to isolate the effect of the variable being tested and determine its impact on the outcome. By keeping all other variables constant, any observed changes in the outcome can be attributed to the manipulated variable. This helps in establishing cause-and-effect relationships and drawing reliable conclusions from the experiment.
8.
Matter is
Correct Answer
C. Anything that takes up space and has mass.
Explanation
The correct answer is "anything that takes up space and has mass." This answer is the most comprehensive and inclusive, as it encompasses both solids and liquids, and emphasizes the fundamental characteristics of matter - occupying space and having mass. It also allows for the possibility of other forms of matter that may not be explicitly mentioned in the options.
9.
What i the chemical formula for iron (III) oxide?
Correct Answer
D. Fe2O3
Explanation
Iron (III) oxide is a compound composed of iron (Fe) and oxygen (O). The Roman numeral III in the name indicates that iron has a +3 oxidation state in this compound. The chemical formula Fe2O3 represents two iron atoms bonded with three oxygen atoms, which is the correct formula for iron (III) oxide.
10.
Which of the following is a mixture?
Correct Answer
A. Air
Explanation
Air is a mixture because it is composed of various gases such as nitrogen, oxygen, carbon dioxide, and small amounts of other gases. These gases are not chemically combined and can be separated from each other through various methods. Therefore, air is considered a mixture rather than a pure substance.
11.
Compounds and elements are
Correct Answer
C. Pure substances.
Explanation
Compounds and elements are classified as pure substances because they consist of only one type of particle. Compounds are made up of two or more different elements chemically bonded together, while elements are composed of identical atoms. Both compounds and elements have fixed compositions and distinct properties, distinguishing them from mixtures. This classification does not imply that compounds and elements are always solids, as they can exist in different states of matter depending on temperature and pressure.
12.
Which of the following is a physical change?
Correct Answer
A. Melting ice cubes
Explanation
Melting ice cubes is a physical change because it involves a change in the state of matter from solid to liquid without altering the chemical composition of the substance. The ice cubes are still made up of water molecules, but they have transitioned from a solid state to a liquid state due to an increase in temperature.
13.
If you add oil to water and shake the two liquids together, you will form a
Correct Answer
A. Heterogeneous mixture.
Explanation
When oil is added to water and shaken together, they do not blend or dissolve completely. Instead, they form separate layers, with the oil floating on top of the water. This indicates that the oil and water do not mix at a molecular level and remain as distinct phases. Therefore, the resulting mixture is a heterogeneous mixture, which is a combination of two or more substances that can be visibly distinguished.
14.
Which of the following assumptions is NOT part of the part of the kinetic theory?
Correct Answer
B. Particles are smaller at lower temperature.
Explanation
The kinetic theory assumes that all matter is made up of tiny, invisible particles and that these particles are always moving. It also states that particles move faster at higher temperatures. However, it does not assume that particles are smaller at lower temperatures. The size of particles is not directly related to temperature in the kinetic theory.
15.
During which change of state do atoms or molecules become more ordered?
Correct Answer
B. Condensation
Explanation
Condensation is the change of state in which a gas or vapor transforms into a liquid. During condensation, the atoms or molecules come closer together and form orderly arrangements, resulting in a more ordered state compared to the gaseous phase. This is because the energy of the particles decreases, causing them to slow down and stick together. Therefore, condensation is the process in which atoms or molecules become more ordered.
16.
Which of the following describes what happens as the temperature of a gas in a balloon increases?
Correct Answer
A. The volume of the gas increases and the speed of the particles in increases.
Explanation
As the temperature of a gas in a balloon increases, the average kinetic energy of the gas particles also increases. This increase in kinetic energy causes the gas particles to move faster and collide more frequently with the walls of the balloon. As a result, the pressure exerted by the gas on the walls of the balloon increases, leading to an increase in volume. Therefore, the correct answer is that the volume of the gas increases and the speed of the particles increases.
17.
Fluid pressure is always directed
Correct Answer
D. In all direction.
Explanation
Fluid pressure is always directed in all directions because fluids are capable of exerting pressure equally in all directions. This is due to the fact that the particles in a fluid are free to move and can transmit force in any direction. When a fluid is at rest, the pressure it exerts is distributed uniformly in all directions, resulting in a balanced pressure throughout the fluid. This property allows fluids to transmit pressure evenly and is the reason why fluids can exert pressure on objects submerged in them from all sides.
18.
Materials that can flow to fit their containers include
Correct Answer
C. Both gases and liquids.
Explanation
Both gases and liquids have the ability to flow and take the shape of their containers. Gases are able to fill the entire container they are in, while liquids maintain a fixed volume but can take the shape of the container they are poured into. Therefore, both gases and liquids can adapt and flow to fit their containers.
19.
If an object weighing 50 N displaces a volume of water with a weight of 10 N, what is the buoyant force on the object?
Correct Answer
A. 10 N
Explanation
The buoyant force on an object is equal to the weight of the fluid displaced by the object. In this case, the object displaces a volume of water with a weight of 10 N. Therefore, the buoyant force on the object is also 10 N.
20.
Which of Dalton's statements about the atom was later proven false?
Correct Answer
A. Atoms cannot be subdivided.
Explanation
Dalton's statement that "atoms cannot be subdivided" was later proven false. The discovery of subatomic particles such as protons, neutrons, and electrons showed that atoms are indeed made up of smaller particles. This led to the development of the atomic model, which explains the structure of atoms and their subatomic components.
21.
Which statement is NOT true of Bohr's model of the atom?
Correct Answer
C. An electron's path is not known exactly.
Explanation
Bohr's model of the atom states that electrons orbit the nucleus, similar to how planets orbit the sun. It also suggests that electrons exist in specific energy levels. However, one of the key principles of Bohr's model is that the exact path or trajectory of an electron cannot be known precisely. This is due to the uncertainty principle in quantum mechanics, which states that it is impossible to simultaneously know both the position and momentum of a particle with absolute certainty. Therefore, the statement "An electron's path is not known exactly" is true and not false.
22.
According to the moderns model of the atom,
Correct Answer
A. Moving electrons form an electron cloud.
Explanation
According to the modern model of the atom, electrons do not move in fixed orbits around the nucleus like planets around the sun. Instead, they exist in regions of space called electron clouds. These electron clouds represent the probability of finding an electron in a particular region around the nucleus. The electrons are constantly in motion within these clouds, creating a fuzzy, cloud-like appearance rather than a specific path or orbit. This model helps to explain the behavior and properties of atoms more accurately than the previous model of fixed electron orbits.
23.
If an atom has a mass of 11 amu and contains five electrons, it's atomic number must be
Correct Answer
D. 5.
Explanation
The atomic number of an atom is equal to the number of protons in its nucleus. Since the atom in question has five electrons, it must also have five protons in order to maintain a neutral charge. Therefore, the atomic number of this atom is 5.
24.
Which statement about atoms of elements in the same group of the periodic table is true?
Correct Answer
C. They have similar chemical properties.
Explanation
Atoms of elements in the same group of the periodic table have similar chemical properties because they have the same number of valence electrons. Valence electrons are the outermost electrons involved in chemical bonding, and they determine the reactivity and chemical behavior of an element. Elements in the same group have the same number of valence electrons, which leads to similar chemical properties. This is why elements in the same group often exhibit similar trends in their reactivity, bonding, and the types of compounds they form.
25.
The majority of elements in the periodic table are
Correct Answer
B. Conductors.
Explanation
The majority of elements in the periodic table are conductors. This is because the majority of elements are metals, and metals are known for their ability to conduct electricity and heat. Conductors have a high number of free electrons that can easily move through the material, allowing for the flow of electric current. Nonmetals, on the other hand, are poor conductors of electricity and heat. Noble gases are a group of nonmetals and are known for their low reactivity and lack of conductivity. Synthetic elements are man-made and can have various properties, but they are not the majority in the periodic table.
26.
An atom of which of the following elements is unlikely to form a positively charged ion?
Correct Answer
B. Selenium, Se
Explanation
Selenium, Se, is unlikely to form a positively charged ion because it belongs to the nonmetal group on the periodic table. Nonmetals tend to gain electrons to achieve a stable electron configuration and form negatively charged ions. Therefore, it is unlikely for selenium to lose electrons and form a positively charged ion.
27.
Which of the following statements about krypton is NOT true?
Correct Answer
C. One mole of krypton atoms has a mass of 41.90 g.
Explanation
The molar mass of krypton is actually 83.79 g/mol Kr, which is stated correctly in the question. The atomic number of krypton is 36, which is also stated correctly in the question. Krypton is indeed a noble gas, which is true according to the question. However, the statement that one mole of krypton atoms has a mass of 41.90 g is not true. The correct molar mass of krypton is 83.79 g/mol Kr, which means that one mole of krypton atoms would have a mass of 83.79 g, not 41.90 g.
28.
Compounds are different from mixtures because
Correct Answer
A. Compounds are held together by chemical bonds.
Explanation
Compounds are different from mixtures because they are held together by chemical bonds. In a compound, the atoms of different elements are chemically bonded to form a new substance with unique properties. This chemical bonding is what distinguishes compounds from mixtures, where the substances are simply physically combined and can be separated without any chemical changes. In a mixture, each substance retains its own properties, whereas in a compound, the original substances undergo a chemical reaction to form a new substance with different properties.
29.
Crystals of table salt, called sodium chloride, are
Correct Answer
B. Made of a network of ions.
Explanation
Table salt, or sodium chloride, forms a crystalline structure composed of a network of ions. In this structure, sodium ions (Na+) and chloride ions (Cl-) are arranged in a repeating pattern, held together by strong electrostatic forces of attraction. This arrangement of ions gives the crystal its characteristic shape and structure. The other options, such as molecules, chemically similar to sugar crystals, or weak solids, do not accurately describe the composition or structure of table salt crystals.
30.
Ionic solids
Correct Answer
C. Have a very regular structure.
Explanation
Ionic solids have a very regular structure because they are formed by a network of ions that have the same charge. The regular arrangement of ions in an ionic solid leads to a repeating pattern, resulting in a crystal lattice structure. This regularity gives ionic solids their characteristic properties, such as high melting points and brittleness. Unlike molecular solids, which have a less organized structure, the strong electrostatic forces between ions in an ionic solid require a regular arrangement to maintain stability.
31.
Which substance has ionic bonds?
Correct Answer
C. KCl
Explanation
KCl has ionic bonds. Ionic bonds occur between a metal and a non-metal, where one atom donates an electron to the other, resulting in the formation of positively charged ions (cations) and negatively charged ions (anions) which are held together by electrostatic attraction. In the case of KCl, potassium (K) donates an electron to chlorine (Cl), forming K+ and Cl- ions, which are attracted to each other, creating an ionic bond. CO, CO2, and O2 do not have ionic bonds as they consist of covalent bonds, where electrons are shared between atoms.
32.
All organic compounds
Correct Answer
D. Have atoms connected by covalent bonds.
Explanation
The correct answer is "have atoms connected by covalent bonds." Covalent bonds are formed when atoms share electrons, and this type of bonding is characteristic of organic compounds. Organic compounds can contain carbon, hydrogen, and other elements such as oxygen, nitrogen, and sulfur. They can be found in living organisms, but they can also be synthesized in a laboratory. Therefore, the statement that all organic compounds have atoms connected by covalent bonds is a more accurate and inclusive description compared to the other options provided.
33.
When a chemical reaction occurs, atoms are never
Correct Answer
C. Destroyed.
Explanation
When a chemical reaction occurs, atoms are never destroyed. In a chemical reaction, the atoms present in the reactants rearrange to form new products. The total number of atoms remains the same before and after the reaction, following the law of conservation of mass. Atoms can be ionized, meaning they gain or lose electrons to form ions, but they are not destroyed.
34.
In an exothermic reaction,
Correct Answer
D. All of the above.
Explanation
In an exothermic reaction, all of the above statements are true. Energy is conserved, meaning it is neither created nor destroyed during the reaction. The formation of bonds in the product releases more energy than is required to break the bonds in the reactants, resulting in a net release of energy. This energy is released as bonds form, leading to an overall release of energy in the reaction.
35.
Which of the following is a homogeneous mixture?
Correct Answer
C. Salt water
Explanation
Salt water is a homogeneous mixture because it has a uniform composition throughout. In salt water, the salt (solute) is evenly distributed in the water (solvent), resulting in a solution with no visible separation of components. This is in contrast to the other options listed, such as tossed salad, soil, and vegetable soup, which are heterogeneous mixtures where the components are not evenly distributed and can be visually distinguished.
36.
If the label on a bottle of medicine reads "shake well before using," the medicine is probably a
Correct Answer
A. Suspension.
Explanation
The label on a bottle of medicine instructing to "shake well before using" suggests that the medicine is a suspension. Suspensions are mixtures in which solid particles are dispersed in a liquid, and they tend to settle over time. Shaking the bottle helps to redistribute the solid particles throughout the liquid, ensuring a consistent dose of the medicine. Solutions, colloids, and gels do not typically require shaking before use, making suspension the most likely option.
37.
Which of the following materials is an example of a solid dessolved in another solid?
Correct Answer
B. Bronze
Explanation
Bronze is an alloy made by combining copper and tin, both of which are solid metals. In this case, the solid copper is dissolved in the solid tin, resulting in a solid solution. Smoke is a mixture of solid particles and gases, not a solid dissolved in another solid. Mayonnaise is a mixture of liquid oil and other ingredients, also not a solid dissolved in another solid. Ice is a solid form of water, but it is not dissolved in another solid material. Therefore, bronze is the only material in the given options that fits the description of a solid dissolved in another solid.
38.
The dispersed particles of a suspension are ___________than the particles of a colloid.
Correct Answer
A. Larger
Explanation
The dispersed particles of a suspension are larger than the particles of a colloid because suspensions consist of solid particles that are typically visible to the naked eye and settle down over time due to gravity. On the other hand, colloids have smaller particles that are not easily visible and remain dispersed in the medium due to the repulsive forces between them.
39.
To dissolve a substance, a solvent must attract particles of the substance more strongly than the ___________ attract each other.
Correct Answer
D. Solute particles
Explanation
In order for a substance to dissolve, the solvent must be able to attract and separate the particles of the substance. The solute particles are the particles of the substance that need to be dissolved, and the solvent must attract them more strongly than they attract each other. This allows the solvent to break apart the solute particles and incorporate them into its own structure, resulting in a homogeneous mixture.
40.
To increase the solubility of a solid substance in a solvent, you could
Correct Answer(s)
B. Heat the solution.
C. Stir the solution.
Explanation
To increase the solubility of a solid substance in a solvent, heating the solution can be effective because it increases the kinetic energy of the particles, causing them to move faster and collide more frequently, which in turn increases the rate of dissolution. Stirring the solution can also increase solubility by promoting the mixing of the solute and solvent, ensuring that fresh solvent comes into contact with the solute, and reducing the concentration gradient at the surface of the solute particles. Adding more solute would not increase solubility, as it would exceed the saturation point and lead to the formation of a precipitate. Lowering the pressure would have no effect on the solubility of a solid substance in a solvent.
41.
A solution is _________ if it contains as much dissolved solute as it will hold under a given set of conditions.
Correct Answer
A. Saturated.
Explanation
A saturated solution is one that has reached its maximum capacity to dissolve solute under specific conditions. It cannot dissolve any more solute, and any additional solute added will remain undissolved at the bottom of the solution.
42.
Gases are more soluble in liquids when the pressure is __________ and the temperature is _________.
Correct Answer
B. High, low
Explanation
Gases are more soluble in liquids when the pressure is high and the temperature is low. This is because high pressure increases the number of gas molecules that come into contact with the liquid, increasing the chances of them dissolving. On the other hand, low temperature reduces the kinetic energy of the gas molecules, making them move slower and facilitating their interaction with the liquid, leading to increased solubility.
43.
The boiling point of a solution of sugar in water is ____________ the boiling point of water.
Correct Answer
A. Higher than
Explanation
When sugar is dissolved in water, it forms a solution. This solution has a higher boiling point compared to pure water. This is because the presence of sugar molecules disrupts the intermolecular forces between water molecules, making it harder for them to escape into the gas phase. As a result, more heat energy is required to break these stronger bonds and raise the temperature of the solution to its boiling point. Therefore, the boiling point of a solution of sugar in water is higher than the boiling point of water.
44.
Which ions does an acid fomr in solution?
Correct Answer
B. Hydronium
Explanation
When an acid dissolves in water, it releases hydrogen ions (H+). These hydrogen ions then combine with water molecules to form hydronium ions (H3O+). Therefore, the correct answer is hydronium.
45.
Which ions does a base form in solution?
Correct Answer
C. Hydroxide
Explanation
A base forms hydroxide ions in solution. When a base dissolves in water, it releases hydroxide ions (OH-) into the solution. These hydroxide ions are responsible for the basic properties of the solution, such as the ability to neutralize acids and to turn litmus paper blue. Therefore, hydroxide is the correct answer as it is the ion formed by a base in solution.
46.
When a solution of nitric acid is added to a solution of calcium hydroxide, the salt formed has the formula
Correct Answer
A. Ca(NO3)2.
Explanation
When nitric acid (HNO3) is added to calcium hydroxide (Ca(OH)2), a neutralization reaction occurs. The hydrogen ions (H+) from the nitric acid react with the hydroxide ions (OH-) from the calcium hydroxide to form water (H2O). The remaining ions, calcium (Ca2+) and nitrate (NO3-), combine to form the salt calcium nitrate (Ca(NO3)2). Therefore, the correct formula for the salt formed is Ca(NO3)2.
47.
An antacid relieves an overly acidic stomach because antacids are
Correct Answer
C. Basic.
Explanation
Antacids relieve an overly acidic stomach because they are basic. Basic substances have a higher pH level than acidic substances, so when antacids are consumed, they neutralize the excess acid in the stomach, providing relief from symptoms such as heartburn and indigestion. By raising the pH level, antacids help to balance the acidity in the stomach, promoting a more comfortable digestive environment.
48.
Detergents have replaced soap in many uses because detergents
Correct Answer
B. Do not form insoluble substances.
Explanation
Detergents have replaced soap in many uses because they do not form insoluble substances. Unlike soap, which can form scum and residue in hard water, detergents are designed to be water-soluble and do not leave behind any insoluble substances. This makes detergents more effective in cleaning and prevents the build-up of residue on surfaces.
49.
Which of the following ionic equations best represents a neutralization reaction?
Correct Answer
D. OH- + H3O+ --> 2H2O
Explanation
The given equation OH- + H3O+ --> 2H2O represents a neutralization reaction because it involves the combination of a hydroxide ion (OH-) and a hydronium ion (H3O+), which are both acidic and basic species respectively. When they react, they form water molecules (H2O), which is a neutral product. This reaction is commonly known as the self-ionization of water, where the hydronium ion donates a proton (H+) to the hydroxide ion, resulting in the formation of water.
50.
Bleach removes stains by
Correct Answer
A. Changing the color of the stain.
Explanation
Bleach removes stains by changing the color of the stain. When bleach comes into contact with a stain, it reacts chemically with the pigments in the stain, causing them to become colorless or less visible. This change in color helps to remove the stain, as it alters the appearance of the stain and makes it less noticeable. Bleach does not cover the stain or disinfect it, nor does it physically remove the stain-causing substances.