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NDQ_016500 | the chemical formula for the compound that consists of barium ions (ba+2) and oxide ions (o-2) is | a. oba, b. o2ba2, c. ba2o2, d. bao | d | Lesson: chemical formula
Representing Compounds:
In a chemical formula, the elements in a compound are represented by their chemical symbols, and the ratio of different elements is represented by subscripts. Consider the compound water as an example. Each water molecule contains two hydrogen atoms and one oxygen atom.... |
NDQ_016512 | a chemical reaction changes some substances into other substances with different chemical properties. | a. true, b. false | a | Lesson: chemical reaction overview
What Is a Chemical Reaction:
A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be ele... |
NDQ_016515 | the substances involved in a chemical reaction may be elements or compounds. | a. true, b. false | a | Lesson: chemical reaction overview
What Is a Chemical Reaction:
A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be ele... |
NDQ_016517 | during a chemical reaction | a. chemical bonds break, b. matter is destroyed, c. new atoms form, d. two of the above | a | Lesson: chemical reaction overview
What Is a Chemical Reaction:
A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be ele... |
NDQ_016518 | which of the following represents a synthesis reaction? | a. 2h2 + o2 2h2o, b. 2k + 2h2o 2koh + h2, c. 2nacl 2na + cl2, d. none of the above | a | Lesson: chemical reaction overview
What Is a Chemical Reaction:
A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be ele... |
NDQ_016519 | which type of reaction is represented by the following chemical equation? ch4 + 2o2 co2 + 2h2o | a. combustion reaction, b. decomposition reaction, c. single replacement reaction, d. double replacement reaction | a | Lesson: chemical reaction overview
What Is a Chemical Reaction:
A chemical reaction is a process in which some substances change into different substances. Substances that start a chemical reaction are called reactants. Substances that are produced in the reaction are called products. Reactants and products can be ele... |
NDQ_016523 | factors that affect the rate of a chemical reaction include | a. concentration of reactants, b. surface area of reactants, c. temperature of reactants, d. all of the above | d | Lesson: chemical reaction rate
How Fast Does It Go:
How fast a chemical reaction occurs is called the reaction rate. Several factors affect the rate of a given chemical reaction. They include the: temperature of reactants. concentration of reactants. surface area of reactants. presence of a catalyst.
Temperature of ... |
NDQ_016524 | warmer reactants react more quickly than cooler reactants. | a. true, b. false | a | Lesson: chemical reaction rate
How Fast Does It Go:
How fast a chemical reaction occurs is called the reaction rate. Several factors affect the rate of a given chemical reaction. They include the: temperature of reactants. concentration of reactants. surface area of reactants. presence of a catalyst.
Temperature of ... |
NDQ_016529 | food spoils faster at higher temperatures because heat is a catalyst. | a. true, b. false | b | Lesson: chemical reaction rate
How Fast Does It Go:
How fast a chemical reaction occurs is called the reaction rate. Several factors affect the rate of a given chemical reaction. They include the: temperature of reactants. concentration of reactants. surface area of reactants. presence of a catalyst.
Temperature of ... |
NDQ_016530 | which statement is true about any catalyst? | a. it is a reactant in a chemical reaction, b. it is used up in a chemical reaction, c. it can speed up many chemical reactions, d. all of the above | c | Lesson: chemical reaction rate
How Fast Does It Go:
How fast a chemical reaction occurs is called the reaction rate. Several factors affect the rate of a given chemical reaction. They include the: temperature of reactants. concentration of reactants. surface area of reactants. presence of a catalyst.
Temperature of ... |
NDQ_016531 | warmer reactants have more energy and move faster. | a. true, b. false | a | Lesson: chemical reaction rate
How Fast Does It Go:
How fast a chemical reaction occurs is called the reaction rate. Several factors affect the rate of a given chemical reaction. They include the: temperature of reactants. concentration of reactants. surface area of reactants. presence of a catalyst.
Temperature of ... |
NDQ_016535 | all compounds consist of a fixed ratio of elements. | a. true, b. false | a | Lesson: chemistry of compounds
What Are Compounds:
A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions th... |
NDQ_016538 | covalent compounds are compounds that | a. consist only of nonmetallic elements, b. have atoms that share electrons, c. exist as individual molecules, d. all of the above | d | Lesson: chemistry of compounds
What Are Compounds:
A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions th... |
NDQ_016539 | water is an example of a covalent compound. | a. true, b. false | a | Lesson: chemistry of compounds
What Are Compounds:
A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions th... |
NDQ_016540 | ionic compounds are compounds that | a. consist only of metallic elements, b. have atoms that transfer electrons, c. exist as individual ions, d. all of the above | b | Lesson: chemistry of compounds
What Are Compounds:
A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions th... |
NDQ_016541 | carbon dioxide is an example of an ionic compound. | a. true, b. false | b | Lesson: chemistry of compounds
What Are Compounds:
A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions th... |
NDQ_016542 | a rainbow includes all the colors of visible light. | a. true, b. false | a | Lesson: color
Wavelength and Color:
Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light determines the color that the light appears. As you can see in the Figure 1.1, light with the longest wavelength appears red, and light with the shortest wavelength app... |
NDQ_016543 | visible light includes all the wavelengths of light that the human eye can detect. | a. true, b. false | a | Lesson: color
Wavelength and Color:
Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light determines the color that the light appears. As you can see in the Figure 1.1, light with the longest wavelength appears red, and light with the shortest wavelength app... |
NDQ_016548 | leaves appear green because they | a. absorb only green light, b. reflect only green light, c. transmit only green light, d. none of the above | b | Lesson: color
Wavelength and Color:
Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light determines the color that the light appears. As you can see in the Figure 1.1, light with the longest wavelength appears red, and light with the shortest wavelength app... |
NDQ_016549 | if only blue light strikes green leaves, the leaves appear | a. green, b. blue, c. black, d. white | c | Lesson: color
Wavelength and Color:
Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light determines the color that the light appears. As you can see in the Figure 1.1, light with the longest wavelength appears red, and light with the shortest wavelength app... |
NDQ_016550 | primary colors of light include | a. red, b. cyan, c. magenta, d. all of the above | a | Lesson: color
Wavelength and Color:
Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light determines the color that the light appears. As you can see in the Figure 1.1, light with the longest wavelength appears red, and light with the shortest wavelength app... |
NDQ_016551 | primary colors of pigments include | a. yellow, b. blue, c. green, d. none of the above | a | Lesson: color
Wavelength and Color:
Visible light is light that has wavelengths that can be detected by the human eye. The wavelength of visible light determines the color that the light appears. As you can see in the Figure 1.1, light with the longest wavelength appears red, and light with the shortest wavelength app... |
NDQ_016555 | the net force acting on you when you sit still in a chair is zero. | a. true, b. false | a | Lesson: combining forces
Speed of Light and Matter Advanced Topic:
You have probably heard of the famous equation E = mc2 . The "E" represent the amount of energy. The "m" represents mass. The "c" represent the speed of light. Writing a "c" is much easier than writing the actual speed of light. The speed of light is a... |
NDQ_016556 | when two forces act on an object in opposite directions, you calculate the net force by | a. dividing the two forces, b. subtracting the two forces, c. finding the average of the two forces, d. none of the above | b | Lesson: combining forces
Speed of Light and Matter Advanced Topic:
You have probably heard of the famous equation E = mc2 . The "E" represent the amount of energy. The "m" represents mass. The "c" represent the speed of light. Writing a "c" is much easier than writing the actual speed of light. The speed of light is a... |
NDQ_016557 | when two forces act on an object in the same direction, you calculate the net force by | a. adding the two forces, b. multiplying the two forces, c. finding the larger of the two forces, d. none of the above | a | Lesson: combining forces
Speed of Light and Matter Advanced Topic:
You have probably heard of the famous equation E = mc2 . The "E" represent the amount of energy. The "m" represents mass. The "c" represent the speed of light. Writing a "c" is much easier than writing the actual speed of light. The speed of light is a... |
NDQ_016559 | when two forces act on the same object in opposite directions, the net force is always greater than the individual forces. | a. true, b. false | b | Lesson: combining forces
Speed of Light and Matter Advanced Topic:
You have probably heard of the famous equation E = mc2 . The "E" represent the amount of energy. The "m" represents mass. The "c" represent the speed of light. Writing a "c" is much easier than writing the actual speed of light. The speed of light is a... |
NDQ_016560 | when two forces act on the same object in the same direction, the net force is always less than the individual forces. | a. true, b. false | b | Lesson: combining forces
Speed of Light and Matter Advanced Topic:
You have probably heard of the famous equation E = mc2 . The "E" represent the amount of energy. The "m" represents mass. The "c" represent the speed of light. Writing a "c" is much easier than writing the actual speed of light. The speed of light is a... |
NDQ_016566 | most fuels in combustion reactions are compounds called | a. proteins, b. ionic compounds, c. hydrocarbons, d. halogens | c | Lesson: combustion reactions
What Is A Combustion Reaction:
A combustion reaction occurs when a substance reacts quickly with oxygen (O2 ). For example, in the Figure usually referred to as fuel. The products of a complete combustion reaction include carbon dioxide (CO2 ) and water vapor (H2 O). The reaction typically... |
NDQ_016568 | the main component of natural gas is nitrogen. | a. true, b. false | b | Lesson: combustion reactions
What Is A Combustion Reaction:
A combustion reaction occurs when a substance reacts quickly with oxygen (O2 ). For example, in the Figure usually referred to as fuel. The products of a complete combustion reaction include carbon dioxide (CO2 ) and water vapor (H2 O). The reaction typically... |
NDQ_016569 | products of incomplete combustion include only carbon dioxide and water. | a. true, b. false | b | Lesson: combustion reactions
What Is A Combustion Reaction:
A combustion reaction occurs when a substance reacts quickly with oxygen (O2 ). For example, in the Figure usually referred to as fuel. The products of a complete combustion reaction include carbon dioxide (CO2 ) and water vapor (H2 O). The reaction typically... |
NDQ_016583 | some compound machines consist of thousands of simple machines. | a. true, b. false | a | Lesson: compound machine
What Is a Compound Machine:
A compound machine is a machine that consists of more than one simple machine. Some compound machines consist of just two simple machines. You can read below about two examplesthe wheelbarrow and corkscrew. Other compound machines, such as bicycles, consist of many ... |
NDQ_016585 | when you use a wheelbarrow, you apply effort to the | a. wheel, b. axle, c. lever, d. two of the above | d | Lesson: compound machine
What Is a Compound Machine:
A compound machine is a machine that consists of more than one simple machine. Some compound machines consist of just two simple machines. You can read below about two examplesthe wheelbarrow and corkscrew. Other compound machines, such as bicycles, consist of many ... |
NDQ_016587 | a corkscrew consists of | a. two levers, b. a screw, c. a wheel and axle, d. two of the above | d | Lesson: compound machine
What Is a Compound Machine:
A compound machine is a machine that consists of more than one simple machine. Some compound machines consist of just two simple machines. You can read below about two examplesthe wheelbarrow and corkscrew. Other compound machines, such as bicycles, consist of many ... |
NDQ_016588 | all machines must overcome friction. | a. true, b. false | a | Lesson: compound machine
What Is a Compound Machine:
A compound machine is a machine that consists of more than one simple machine. Some compound machines consist of just two simple machines. You can read below about two examplesthe wheelbarrow and corkscrew. Other compound machines, such as bicycles, consist of many ... |
NDQ_016589 | no machine is 100 percent efficient. | a. true, b. false | a | Lesson: compound machine
What Is a Compound Machine:
A compound machine is a machine that consists of more than one simple machine. Some compound machines consist of just two simple machines. You can read below about two examplesthe wheelbarrow and corkscrew. Other compound machines, such as bicycles, consist of many ... |
NDQ_016593 | which of the following is a compound? | a. air, b. oxygen, c. carbon dioxide, d. two of the above | c | Lesson: compounds
What Is a Compound:
A compound is a unique substance that forms when two or more elements combine chemically. For example, the compound carbon dioxide forms when one atom of carbon (grey in the model above) combines with two atoms of oxygen (red in the model). Another example of a compound is water. ... |
NDQ_016594 | a compound always has the same elements in the same proportions. | a. true, b. false | a | Lesson: compounds
What Is a Compound:
A compound is a unique substance that forms when two or more elements combine chemically. For example, the compound carbon dioxide forms when one atom of carbon (grey in the model above) combines with two atoms of oxygen (red in the model). Another example of a compound is water. ... |
NDQ_016595 | the properties of compounds are the same as the properties of the elements that form them. | a. true, b. false | b | Lesson: compounds
What Is a Compound:
A compound is a unique substance that forms when two or more elements combine chemically. For example, the compound carbon dioxide forms when one atom of carbon (grey in the model above) combines with two atoms of oxygen (red in the model). Another example of a compound is water. ... |
NDQ_016598 | which of the following substances is a compound that forms ionic crystals? | a. water, b. sodium chloride, c. carbon dioxide, d. none of the above | b | Lesson: compounds
What Is a Compound:
A compound is a unique substance that forms when two or more elements combine chemically. For example, the compound carbon dioxide forms when one atom of carbon (grey in the model above) combines with two atoms of oxygen (red in the model). Another example of a compound is water. ... |
NDQ_016599 | which of the following gases is a compound that forms molecules? | a. air, b. carbon dioxide, c. oxygen, d. nitrogen | b | Lesson: compounds
What Is a Compound:
A compound is a unique substance that forms when two or more elements combine chemically. For example, the compound carbon dioxide forms when one atom of carbon (grey in the model above) combines with two atoms of oxygen (red in the model). Another example of a compound is water. ... |
NDQ_016601 | a molecule consists of two or more atoms bonded together. | a. true, b. false | a | Lesson: compounds
What Is a Compound:
A compound is a unique substance that forms when two or more elements combine chemically. For example, the compound carbon dioxide forms when one atom of carbon (grey in the model above) combines with two atoms of oxygen (red in the model). Another example of a compound is water. ... |
NDQ_016612 | which statement about energy and chemical reactions is true? | a. all chemical reactions involve energy, b. breaking bonds in reactants requires energy, c. forming bonds in products releases energy, d. all of the above | d | Lesson: conservation of energy in chemical reactions
Energy and Chemical Reactions:
All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Like the combustion reaction in a furnace, some chemical reactions require less energy to break ... |
NDQ_016615 | energy cannot be created or destroyed in chemical reactions. | a. true, b. false | a | Lesson: conservation of energy in chemical reactions
Energy and Chemical Reactions:
All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Like the combustion reaction in a furnace, some chemical reactions require less energy to break ... |
NDQ_016616 | energy cannot change form during chemical reactions. | a. true, b. false | b | Lesson: conservation of energy in chemical reactions
Energy and Chemical Reactions:
All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Like the combustion reaction in a furnace, some chemical reactions require less energy to break ... |
NDQ_016618 | in an endothermic reaction, products have less chemical energy than reactants. | a. true, b. false | b | Lesson: conservation of energy in chemical reactions
Energy and Chemical Reactions:
All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Like the combustion reaction in a furnace, some chemical reactions require less energy to break ... |
NDQ_016620 | when natural gas burns in a furnace | a. energy is released in the form of heat and light, b. it takes more energy to break bonds in reactants than to form bonds in products, c. the natural gas creates energy as it burns, d. two of the above | a | Lesson: conservation of energy in chemical reactions
Energy and Chemical Reactions:
All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Like the combustion reaction in a furnace, some chemical reactions require less energy to break ... |
NDQ_016632 | the letter e in einsteins equation e = mc2 stands for | a. electricity, b. electrons, c. energy, d. efficiency | c | Lesson: conservation of mass and energy in nuclear reactions
Einsteins Equation:
Einsteins equation is possibly the best-known equation of all time. Theres reason for that. The equation is incredibly important. It changed how scientists view energy and matter, which are two of the most basic concepts in all of science... |
NDQ_016634 | the letter c in the equation in question 1 represents a constant. | a. true, b. false | a | Lesson: conservation of mass and energy in nuclear reactions
Einsteins Equation:
Einsteins equation is possibly the best-known equation of all time. Theres reason for that. The equation is incredibly important. It changed how scientists view energy and matter, which are two of the most basic concepts in all of science... |
NDQ_016635 | the speed of light is 300,000 km per hour. | a. true, b. false | b | Lesson: conservation of mass and energy in nuclear reactions
Einsteins Equation:
Einsteins equation is possibly the best-known equation of all time. Theres reason for that. The equation is incredibly important. It changed how scientists view energy and matter, which are two of the most basic concepts in all of science... |
NDQ_016638 | einsteins equation has recently been disproven by real-world evidence. | a. true, b. false | b | Lesson: conservation of mass and energy in nuclear reactions
Einsteins Equation:
Einsteins equation is possibly the best-known equation of all time. Theres reason for that. The equation is incredibly important. It changed how scientists view energy and matter, which are two of the most basic concepts in all of science... |
NDQ_016639 | the amount of energy in a tiny amount of mass is very large. | a. true, b. false | a | Lesson: conservation of mass and energy in nuclear reactions
Einsteins Equation:
Einsteins equation is possibly the best-known equation of all time. Theres reason for that. The equation is incredibly important. It changed how scientists view energy and matter, which are two of the most basic concepts in all of science... |
NDQ_016640 | einsteins equation shows that mass and energy are not conserved in nuclear reactions. | a. true, b. false | b | Lesson: conservation of mass and energy in nuclear reactions
Einsteins Equation:
Einsteins equation is possibly the best-known equation of all time. Theres reason for that. The equation is incredibly important. It changed how scientists view energy and matter, which are two of the most basic concepts in all of science... |
NDQ_016642 | chemical reactions are represented by chemical formulas. | a. true, b. false | b | Lesson: conservation of mass in chemical reactions
Chemical Reactions and Balanced Equations:
A chemical reaction occurs when some substances change chemically to other substances. Chemical reactions are represented by chemical equations. Consider a simple chemical reaction, the burning of methane. In this reaction, m... |
NDQ_016643 | which choice correctly represents the reaction in which methane burns? | a. ch4 + 2o2 co2 + 2h2o, b. 2ch4 + 2o2 co2 + 2h2o, c. ch4 + o2 co2 + h2o, d. none of the above | a | Lesson: conservation of mass in chemical reactions
Chemical Reactions and Balanced Equations:
A chemical reaction occurs when some substances change chemically to other substances. Chemical reactions are represented by chemical equations. Consider a simple chemical reaction, the burning of methane. In this reaction, m... |
NDQ_016650 | the equation h2 + o2 h2o is balanced. | a. true, b. false | b | Lesson: conservation of mass in chemical reactions
Chemical Reactions and Balanced Equations:
A chemical reaction occurs when some substances change chemically to other substances. Chemical reactions are represented by chemical equations. Consider a simple chemical reaction, the burning of methane. In this reaction, m... |
NDQ_016651 | which equation shows that mass is conserved in the chemical reaction? | a. 2al + 2o2 2al2o3, b. 2al + o2 al2o3, c. 4al + 3o2 2al2o3, d. none of the above | c | Lesson: conservation of mass in chemical reactions
Chemical Reactions and Balanced Equations:
A chemical reaction occurs when some substances change chemically to other substances. Chemical reactions are represented by chemical equations. Consider a simple chemical reaction, the burning of methane. In this reaction, m... |
NDQ_016652 | heat is the transfer of thermal energy. | a. true, b. false | a | Lesson: convection
Defining Convection:
Convection is the transfer of thermal energy by particles moving through a fluid (either a gas or a liquid). Thermal energy is the total kinetic energy of moving particles of matter, and the transfer of thermal energy is called heat. Convection is one of three ways that thermal ... |
NDQ_016656 | when particles of matter in one part of a fluid gain thermal energy they | a. move more quickly, b. have more collisions, c. spread farther apart, d. all of the above | d | Lesson: convection
Defining Convection:
Convection is the transfer of thermal energy by particles moving through a fluid (either a gas or a liquid). Thermal energy is the total kinetic energy of moving particles of matter, and the transfer of thermal energy is called heat. Convection is one of three ways that thermal ... |
NDQ_016657 | when particles are more spread out, they have higher density. | a. true, b. false | b | Lesson: convection
Defining Convection:
Convection is the transfer of thermal energy by particles moving through a fluid (either a gas or a liquid). Thermal energy is the total kinetic energy of moving particles of matter, and the transfer of thermal energy is called heat. Convection is one of three ways that thermal ... |
NDQ_016658 | higher density particles sink downward through a fluid. | a. true, b. false | a | Lesson: convection
Defining Convection:
Convection is the transfer of thermal energy by particles moving through a fluid (either a gas or a liquid). Thermal energy is the total kinetic energy of moving particles of matter, and the transfer of thermal energy is called heat. Convection is one of three ways that thermal ... |
NDQ_016661 | convection currents transfer thermal energy through earths | a. oceans, b. atmosphere, c. molten rock, d. all of the above | d | Lesson: convection
Defining Convection:
Convection is the transfer of thermal energy by particles moving through a fluid (either a gas or a liquid). Thermal energy is the total kinetic energy of moving particles of matter, and the transfer of thermal energy is called heat. Convection is one of three ways that thermal ... |
NDQ_016665 | work as defined in physics always involves | a. force, b. motion, c. energy, d. all of the above | d | Lesson: cooling systems
Purpose of a Cooling System:
A refrigerator is an example of a cooling system. Another example is an air conditioner. The purpose of any cooling system is to transfer thermal energy in order to keep things cool. A refrigerator, for example, transfers thermal energy from the cool air inside the ... |
NDQ_016666 | most cooling systems get energy from electricity. | a. true, b. false | a | Lesson: cooling systems
Purpose of a Cooling System:
A refrigerator is an example of a cooling system. Another example is an air conditioner. The purpose of any cooling system is to transfer thermal energy in order to keep things cool. A refrigerator, for example, transfers thermal energy from the cool air inside the ... |
NDQ_016667 | in a cooling system, the refrigerant | a. has a high boiling point, b. absorbs thermal energy from air inside the refrigerator, c. pumps cool air into the refrigerator, d. two of the above | b | Lesson: cooling systems
Purpose of a Cooling System:
A refrigerator is an example of a cooling system. Another example is an air conditioner. The purpose of any cooling system is to transfer thermal energy in order to keep things cool. A refrigerator, for example, transfers thermal energy from the cool air inside the ... |
NDQ_016668 | the refrigerant changes between solid and liquid states as it passes through the refrigerator. | a. true, b. false | b | Lesson: cooling systems
Purpose of a Cooling System:
A refrigerator is an example of a cooling system. Another example is an air conditioner. The purpose of any cooling system is to transfer thermal energy in order to keep things cool. A refrigerator, for example, transfers thermal energy from the cool air inside the ... |
NDQ_016669 | as a liquid the refrigerant transfers thermal energy to the outside air. | a. true, b. false | b | Lesson: cooling systems
Purpose of a Cooling System:
A refrigerator is an example of a cooling system. Another example is an air conditioner. The purpose of any cooling system is to transfer thermal energy in order to keep things cool. A refrigerator, for example, transfers thermal energy from the cool air inside the ... |
NDQ_016673 | in covalent bonds, the atoms that form bonds | a. may be metals or nonmetals, b. transfer electrons, c. may both be the same element, d. all of the above | c | Lesson: covalent bonding
Sharing Electrons:
A covalent bond is the force of attraction that holds together two atoms that share a pair of valence electrons. The shared electrons are attracted to the nuclei of both atoms. This forms a molecule consisting of two or more atoms. Covalent bonds form only between atoms of n... |
NDQ_016674 | electrons in covalent bonds are attracted to the nucleus of just one atom. | a. true, b. false | b | Lesson: covalent bonding
Sharing Electrons:
A covalent bond is the force of attraction that holds together two atoms that share a pair of valence electrons. The shared electrons are attracted to the nuclei of both atoms. This forms a molecule consisting of two or more atoms. Covalent bonds form only between atoms of n... |
NDQ_016676 | a covalent bond always includes a pair of electrons. | a. true, b. false | a | Lesson: covalent bonding
Sharing Electrons:
A covalent bond is the force of attraction that holds together two atoms that share a pair of valence electrons. The shared electrons are attracted to the nuclei of both atoms. This forms a molecule consisting of two or more atoms. Covalent bonds form only between atoms of n... |
NDQ_016677 | elements that form diatomic molecules include | a. oxygen, b. hydrogen, c. chlorine, d. all of the above | d | Lesson: covalent bonding
Sharing Electrons:
A covalent bond is the force of attraction that holds together two atoms that share a pair of valence electrons. The shared electrons are attracted to the nuclei of both atoms. This forms a molecule consisting of two or more atoms. Covalent bonds form only between atoms of n... |
NDQ_016679 | the formation of one or more covalent bonds always results in a covalent compound. | a. true, b. false | b | Lesson: covalent bonding
Sharing Electrons:
A covalent bond is the force of attraction that holds together two atoms that share a pair of valence electrons. The shared electrons are attracted to the nuclei of both atoms. This forms a molecule consisting of two or more atoms. Covalent bonds form only between atoms of n... |
NDQ_016680 | which of the following is a covalent compound? | a. h2o, b. nacl, c. o2, d. two of the above | a | Lesson: covalent bonding
Sharing Electrons:
A covalent bond is the force of attraction that holds together two atoms that share a pair of valence electrons. The shared electrons are attracted to the nuclei of both atoms. This forms a molecule consisting of two or more atoms. Covalent bonds form only between atoms of n... |
NDQ_016683 | forms of crystalline carbon include | a. coal, b. graphite, c. charcoal, d. two of the above | b | Lesson: crystalline carbon
What Are the Forms of Carbon:
Graphite is one of three forms of crystalline, or crystal-forming, carbon. Carbon also exists in an amorphous, or shapeless, form in substances such as coal and charcoal. Different forms of the same element are called allotropes. Besides graphite, the other allo... |
NDQ_016688 | the form of carbon in question 6 has been found in meteorites. | a. true, b. false | a | Lesson: crystalline carbon
What Are the Forms of Carbon:
Graphite is one of three forms of crystalline, or crystal-forming, carbon. Carbon also exists in an amorphous, or shapeless, form in substances such as coal and charcoal. Different forms of the same element are called allotropes. Besides graphite, the other allo... |
NDQ_016689 | diamonds are used for | a. lubricants, b. jewelry, c. blades, d. two of the above | d | Lesson: crystalline carbon
What Are the Forms of Carbon:
Graphite is one of three forms of crystalline, or crystal-forming, carbon. Carbon also exists in an amorphous, or shapeless, form in substances such as coal and charcoal. Different forms of the same element are called allotropes. Besides graphite, the other allo... |
NDQ_016690 | the form of crystalline carbon in which each carbon atom is covalently bonded to three other carbon atoms is | a. diamond, b. graphite, c. charcoal, d. coal | b | Lesson: crystalline carbon
What Are the Forms of Carbon:
Graphite is one of three forms of crystalline, or crystal-forming, carbon. Carbon also exists in an amorphous, or shapeless, form in substances such as coal and charcoal. Different forms of the same element are called allotropes. Besides graphite, the other allo... |
NDQ_016691 | fullerenes are used to make soccer balls. | a. true, b. false | b | Lesson: crystalline carbon
What Are the Forms of Carbon:
Graphite is one of three forms of crystalline, or crystal-forming, carbon. Carbon also exists in an amorphous, or shapeless, form in substances such as coal and charcoal. Different forms of the same element are called allotropes. Besides graphite, the other allo... |
NDQ_016693 | scientists now reject most of daltons atomic theory. | a. true, b. false | b | Lesson: daltons atomic theory
Reintroducing the Atom:
Around 1800, the English chemist John Dalton brought back Democritus ancient idea of the atom. You can see a picture of Dalton 1.1. Dalton grew up in a working-class family. As an adult, he made a living by teaching and just did research in his spare time. Nonethel... |
NDQ_016694 | dalton based his ideas about atoms on his own scientific research. | a. true, b. false | a | Lesson: daltons atomic theory
Reintroducing the Atom:
Around 1800, the English chemist John Dalton brought back Democritus ancient idea of the atom. You can see a picture of Dalton 1.1. Dalton grew up in a working-class family. As an adult, he made a living by teaching and just did research in his spare time. Nonethel... |
NDQ_016695 | dalton investigated | a. pressure of gases, b. ratios of elements in compounds, c. protons and other subatomic particles, d. two of the above | d | Lesson: daltons atomic theory
Reintroducing the Atom:
Around 1800, the English chemist John Dalton brought back Democritus ancient idea of the atom. You can see a picture of Dalton 1.1. Dalton grew up in a working-class family. As an adult, he made a living by teaching and just did research in his spare time. Nonethel... |
NDQ_016696 | according to daltons atomic theory | a. only compounds are made of atoms, b. no two atoms are exactly alike, c. atoms cannot be created or destroyed, d. all of the above | c | Lesson: daltons atomic theory
Reintroducing the Atom:
Around 1800, the English chemist John Dalton brought back Democritus ancient idea of the atom. You can see a picture of Dalton 1.1. Dalton grew up in a working-class family. As an adult, he made a living by teaching and just did research in his spare time. Nonethel... |
NDQ_016697 | dalton thought that atoms consist of smaller particles of matter. | a. true, b. false | b | Lesson: daltons atomic theory
Reintroducing the Atom:
Around 1800, the English chemist John Dalton brought back Democritus ancient idea of the atom. You can see a picture of Dalton 1.1. Dalton grew up in a working-class family. As an adult, he made a living by teaching and just did research in his spare time. Nonethel... |
NDQ_016698 | daltons atomic theory was quickly accepted by most other scientists. | a. true, b. false | a | Lesson: daltons atomic theory
Reintroducing the Atom:
Around 1800, the English chemist John Dalton brought back Democritus ancient idea of the atom. You can see a picture of Dalton 1.1. Dalton grew up in a working-class family. As an adult, he made a living by teaching and just did research in his spare time. Nonethel... |
NDQ_016699 | dalton thought that a given compound always consists of the same kinds of atoms in the same proportions. | a. true, b. false | a | Lesson: daltons atomic theory
Reintroducing the Atom:
Around 1800, the English chemist John Dalton brought back Democritus ancient idea of the atom. You can see a picture of Dalton 1.1. Dalton grew up in a working-class family. As an adult, he made a living by teaching and just did research in his spare time. Nonethel... |
NDQ_016703 | there is a low level of natural radiation in the environment. | a. true, b. false | a | Lesson: dangers and uses of radiation
Radiation in the Environment:
A low level of radiation occurs naturally in the environment. This is called background radiation. One source of background radiation is rocks, which may contain small amounts of radioactive elements such as uranium. Another source is cosmic rays. The... |
NDQ_016704 | sources of background radiation include | a. cosmic rays from space, b. atomic bomb testing, c. nuclear power plants, d. all of the above | a | Lesson: dangers and uses of radiation
Radiation in the Environment:
A low level of radiation occurs naturally in the environment. This is called background radiation. One source of background radiation is rocks, which may contain small amounts of radioactive elements such as uranium. Another source is cosmic rays. The... |
NDQ_016705 | background radiation is generally considered harmful to living things. | a. true, b. false | b | Lesson: dangers and uses of radiation
Radiation in the Environment:
A low level of radiation occurs naturally in the environment. This is called background radiation. One source of background radiation is rocks, which may contain small amounts of radioactive elements such as uranium. Another source is cosmic rays. The... |
NDQ_016706 | radiation can cause damage by | a. knocking electrons out of atoms, b. changing atoms to ions, c. breaking bonds in dna, d. all of the above | d | Lesson: dangers and uses of radiation
Radiation in the Environment:
A low level of radiation occurs naturally in the environment. This is called background radiation. One source of background radiation is rocks, which may contain small amounts of radioactive elements such as uranium. Another source is cosmic rays. The... |
NDQ_016709 | only living things can be harmed by radiation. | a. true, b. false | b | Lesson: dangers and uses of radiation
Radiation in the Environment:
A low level of radiation occurs naturally in the environment. This is called background radiation. One source of background radiation is rocks, which may contain small amounts of radioactive elements such as uranium. Another source is cosmic rays. The... |
NDQ_016713 | which general equation represents a decomposition reaction? | a. a + b ab, b. ab a + b, c. ab + c ac + b, d. ac a + b | b | Lesson: decomposition reactions
What Is A Decomposition Reaction:
A decomposition reaction occurs when one reactant breaks down into two or more products. It can be represented by the general equation: AB A + B In this equation, AB represents the reactant that begins the reaction, and A and B represent the products o... |
NDQ_016714 | products of decomposition reactions are always individual elements. | a. true, b. false | b | Lesson: decomposition reactions
What Is A Decomposition Reaction:
A decomposition reaction occurs when one reactant breaks down into two or more products. It can be represented by the general equation: AB A + B In this equation, AB represents the reactant that begins the reaction, and A and B represent the products o... |
NDQ_016715 | examples of decomposition reactions include | a. 2h2o2 2h2o + o2, b. nh3 + h2o nh4oh, c. 2nacl 2na + cl2, d. two of the above | d | Lesson: decomposition reactions
What Is A Decomposition Reaction:
A decomposition reaction occurs when one reactant breaks down into two or more products. It can be represented by the general equation: AB A + B In this equation, AB represents the reactant that begins the reaction, and A and B represent the products o... |
NDQ_016720 | the reaction 2al2o3 4al + 3o2 is a decomposition reaction. | a. true, b. false | a | Lesson: decomposition reactions
What Is A Decomposition Reaction:
A decomposition reaction occurs when one reactant breaks down into two or more products. It can be represented by the general equation: AB A + B In this equation, AB represents the reactant that begins the reaction, and A and B represent the products o... |
NDQ_016724 | according to democritus, atoms are | a. too small to see, b. indestructible, c. unable to be subdivided, d. all of the above | d | Lesson: democrituss idea of the atom
Cutting the Cheese:
Democritus lived in Greece from about 460 to 370 B.C.E. Like many other ancient Greek philosophers, he spent a lot of time wondering about the natural world. Democritus wondered, for example, what would happen if you cut a chunk of mattersuch as a piece of chees... |
NDQ_016725 | democritus thought that atoms are motionless. | a. true, b. false | b | Lesson: democrituss idea of the atom
Cutting the Cheese:
Democritus lived in Greece from about 460 to 370 B.C.E. Like many other ancient Greek philosophers, he spent a lot of time wondering about the natural world. Democritus wondered, for example, what would happen if you cut a chunk of mattersuch as a piece of chees... |
NDQ_016726 | democritus thought that atoms are separated from each other by empty space. | a. true, b. false | a | Lesson: democrituss idea of the atom
Cutting the Cheese:
Democritus lived in Greece from about 460 to 370 B.C.E. Like many other ancient Greek philosophers, he spent a lot of time wondering about the natural world. Democritus wondered, for example, what would happen if you cut a chunk of mattersuch as a piece of chees... |
NDQ_016729 | what happened to democritus ideas about atoms? | a. they were ridiculed by aristotle, b. they were widely accepted in his own lifetime, c. they were almost forgotten for more than 2000 years, d. two of the above | d | Lesson: democrituss idea of the atom
Cutting the Cheese:
Democritus lived in Greece from about 460 to 370 B.C.E. Like many other ancient Greek philosophers, he spent a lot of time wondering about the natural world. Democritus wondered, for example, what would happen if you cut a chunk of mattersuch as a piece of chees... |
NDQ_016731 | democritus ideas were based on experimental evidence. | a. true, b. false | b | Lesson: democrituss idea of the atom
Cutting the Cheese:
Democritus lived in Greece from about 460 to 370 B.C.E. Like many other ancient Greek philosophers, he spent a lot of time wondering about the natural world. Democritus wondered, for example, what would happen if you cut a chunk of mattersuch as a piece of chees... |
NDQ_016753 | the central tendency of a sample can be represented by the | a. mean, b. median, c. mode, d. any of the above | d | Lesson: descriptive statistics
Using Statistics to Describe a Sample:
The girls in the picture above make up a small samplethere are only four of them. In scientific investigations, samples may include hundreds or even thousands of people or other objects of study. Especially when samples are very large, its important... |
NDQ_016757 | the mean and median of the same set of values are always the same. | a. true, b. false | b | Lesson: descriptive statistics
Using Statistics to Describe a Sample:
The girls in the picture above make up a small samplethere are only four of them. In scientific investigations, samples may include hundreds or even thousands of people or other objects of study. Especially when samples are very large, its important... |
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