instruction stringlengths 5 342 | input stringlengths 18 558 | output stringclasses 7
values | context stringlengths 31 6.57k |
|---|---|---|---|
Wax melting is an example of a chemical reaction. | (A) true (B) false | B | Look carefully at the Figures 1.1, 1.2, and 1.3. All of the photos demonstrate chemical reactions. For each photo, identify a sign that one or more chemical reactions have taken place. A burning campfire can warm you up on a cold day. Dissolving an antacid tablet in water produces a fizzy drink. Adding acid to milk pro... |
The products and reactants of a chemical reaction have different atoms. | (A) true (B) false | B | The reactants and products in a chemical reaction contain the same atoms, but they are rearranged during the reaction. As a result, the atoms are in different combinations in the products than they were in the reactants. This happens because chemical bonds break in the reactants and new chemical bonds form in the produ... |
All chemical reactions are reversible. | (A) true (B) false | B | Because chemical changes produce new substances, they often cannot be undone. For example, you cant change a fried egg back to a raw egg. Some chemical changes can be reversed, but only by other chemical changes. For example, to undo the tarnish on copper pennies, you can place them in vinegar. The acid in the vinegar ... |
Rusting is an example of a chemical change. | (A) true (B) false | A | Most chemical changes are not as dramatic as exploding fireworks, so how can you tell whether a chemical change has occurred? There are usually clues. You just need to know what to look for. A chemical change has probably occurred if bubbles are released, there is a change of color, or an odor is produced. Other clues ... |
Condensation is a type of chemical reaction. | (A) true (B) false | B | The chemical reaction in the Figure 1.2, in which water forms from hydrogen and oxygen, is an example of a synthesis reaction. In this type of reaction, two or more reactants combine to synthesize a single product. There are several other types of chemical reactions, including decomposition, replacement, and combustion... |
A change in temperature is a common sign of a chemical reaction. | (A) true (B) false | A | A change in color is just one of several potential signs that a chemical reaction has occurred. Other potential signs include: Change in temperature-Heat is released or absorbed during the reaction. Production of a gas-Gas bubbles are released during the reaction. Production of a solid-A solid settles out of a liquid s... |
substance produced in a chemical reaction | (A) chemical reaction (B) melting (C) equilibrium (D) chemical bond (E) product (F) rusting (G) reactant | E | 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 elements or compounds. A chemical reaction can be represented by thi... |
force of attraction that breaks and reforms in a chemical reaction | (A) chemical reaction (B) melting (C) equilibrium (D) chemical bond (E) product (F) rusting (G) reactant | D | In chemical reactions, bonds break in the reactants and new bonds form in the products. The reactants and prod- ucts contain the same atoms, but they are rearranged during the reaction. As a result, the atoms are in different combinations in the products than they were in the reactants. Look at the example in Figure 8.... |
substance that starts a chemical reaction | (A) chemical reaction (B) melting (C) equilibrium (D) chemical bond (E) product (F) rusting (G) reactant | G | Some reactions need extra help to occur quickly. They need another substance called a catalyst. A catalyst is a substance that increases the rate of a chemical reaction. A catalyst isnt a reactant, so it isnt changed or used up in the reaction. Therefore, it can catalyze many other reactions. |
example of chemical change | (A) chemical reaction (B) melting (C) equilibrium (D) chemical bond (E) product (F) rusting (G) reactant | F | A chemical change occurs whenever matter changes into an entirely different substance with different chemical properties. A chemical change is also called a chemical reaction. Many complex chemical changes occur to produce the explosions of fireworks. An example of a simpler chemical change is the burning of methane. M... |
balance between opposing changes | (A) chemical reaction (B) melting (C) equilibrium (D) chemical bond (E) product (F) rusting (G) reactant | C | When you walk outside on a cool day, does your body temperature drop? No, your body temperature stays stable at around 98.6 degrees Fahrenheit. Even when the temperature around you changes, your internal temperature stays the same. This ability of the body to maintain a stable internal environment despite a changing en... |
process in which some substances become different substances | (A) chemical reaction (B) melting (C) equilibrium (D) chemical bond (E) product (F) rusting (G) reactant | A | 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 elements or compounds. A chemical reaction can be represented by thi... |
example of a physical change | (A) chemical reaction (B) melting (C) equilibrium (D) chemical bond (E) product (F) rusting (G) reactant | B | A physical change is a change in one or more physical properties of matter without any change in chemical properties. In other words, matter doesnt change into a different substance in a physical change. Examples of physical change include changes in the size or shape of matter. Changes of statefor example, from solid ... |
What do the formation of rust and the formation of cottage cheese have in common? | (A) Both occur very quickly (B) Both involve chemical reactions (C) Both are changes of state (D) Both are physical processes | B | Lets return to the chemical reaction in which iron (Fe) combines with oxygen (O2 ) to form rust, or iron oxide (Fe2 O3 ). The equation for this reaction is: 4Fe+ 3O2 2Fe2 O3 This equation illustrates the use of coefficients to balance chemical equations. A coefficient is a number placed in front of a chemical symbol o... |
Which of the following changes does not involve chemical reactions? | (A) clouds forming (B) candles burning (C) leaves turning color (D) fire extinguishers foaming | A | Not all changes in matter involve chemical reactions. For example, there are no chemical reactions involved in changes of state. When liquid water freezes or evaporates, it is still water. No bonds are broken and no new products are formed. How can you tell whether a change in matter involves a chemical reaction? Often... |
During chemical reactions, atoms are | (A) rearranged (B) created or destroyed (C) changed to new elements (D) two of the above | A | The reactants and products in a chemical reaction contain the same atoms, but they are rearranged during the reaction. As a result, the atoms are in different combinations in the products than they were in the reactants. This happens because chemical bonds break in the reactants and new chemical bonds form in the produ... |
There is no overall change in reactants and products whenever a chemical reaction | (A) goes in just one direction (B) goes in two directions (C) reaches equilibrium (D) proceeds slowly | C | The reactants and products in a chemical reaction contain the same atoms, but they are rearranged during the reaction. As a result, the atoms are in different combinations in the products than they were in the reactants. This happens because chemical bonds break in the reactants and new chemical bonds form in the produ... |
Evidence of chemical reactions include changes in | (A) state (B) color (C) temperature (D) two of the above | D | A change in color is just one of several potential signs that a chemical reaction has occurred. Other potential signs include: Change in temperature-Heat is released or absorbed during the reaction. Production of a gas-Gas bubbles are released during the reaction. Production of a solid-A solid settles out of a liquid s... |
In chemical equations, reactants and products are represented by | (A) plus signs and arrows (B) elements and compounds (C) coefficients and subscripts (D) chemical symbols and chemical formulas | D | A chemical equation is a symbolic representation of a chemical reaction. It is a shorthand way of showing how atoms are rearranged in the reaction. The general form of a chemical equation was introduced in this chapters lesson "Introduction to Chemical Reactions." It is: Reactants ! Products Consider the simple example... |
A shorthand way of showing how atoms are rearranged in a chemical reaction is a chemical | (A) symbol (B) formula (C) equation (D) letter | C | A chemical equation is a symbolic representation of a chemical reaction. It is a shorthand way of showing how atoms are rearranged in the reaction. The general form of a chemical equation was introduced in this chapters lesson "Introduction to Chemical Reactions." It is: Reactants ! Products Consider the simple example... |
When there is more than one reactant in a chemical equation, they are separated by | (A) arrows (B) subscripts (C) plus signs (D) coefficients | C | A chemical equation is a symbolic representation of a chemical reaction. It is a shorthand way of showing how atoms are rearranged in the reaction. The general form of a chemical equation was introduced in this chapters lesson "Introduction to Chemical Reactions." It is: Reactants ! Products Consider the simple example... |
Which chemical equation is not balanced? | (A) 2Na + Cl2 2NaCl (B) C + O2 CO2 (C) NO + O2 2NO2 (D) N2 + 3H2 2NH3 | C | Some chemical equations are more challenging to write. Consider the reaction in which hydrogen (H2 ) and oxygen (O2 ) combine to form water (H2 O). Hydrogen and oxygen are the reactants, and water is the product. To write a chemical equation for this reaction, you would start by writing symbols for the reactants and pr... |
In the reaction represented by the chemical equation 2Cu + O2 2CuO, new bonds are formed in | (A) 2Cu (B) O2 (C) CuO (D) none of the above | C | In chemical reactions, bonds break in the reactants and new bonds form in the products. The reactants and prod- ucts contain the same atoms, but they are rearranged during the reaction. As a result, the atoms are in different combinations in the products than they were in the reactants. Look at the example in Figure 8.... |
If there is more than one product in a chemical equation, the products are separated by | (A) plus signs (B) minus signs (C) equals signs (D) two-way arrows | A | A chemical equation is a symbolic representation of a chemical reaction. It is a shorthand way of showing how atoms are rearranged in the reaction. The general form of a chemical equation was introduced in this chapters lesson "Introduction to Chemical Reactions." It is: Reactants ! Products Consider the simple example... |
What is the missing coefficient in the following chemical equation? CH4 + ?O2 CO2 + 2H2 O | (A) 3 (B) 2 (C) 1 (D) 0 | B | Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction. For example, two molecules of hydrogen would be written as 2H2 . A coefficient of 1 usually isnt written. Co... |
Chemical equations must be balanced because matter cannot be | (A) created (B) destroyed (C) changed (D) two of the above | D | Why must chemical equations be balanced? Its the law! Matter cannot be created or destroyed in chemical reactions. This is the law of conservation of mass. In every chemical reaction, the same mass of matter must end up in the products as started in the reactants. Balanced chemical equations show that mass is conserved... |
Which chemical equation is balanced? | (A) 2Na + Cl2 2NaCl (B) Na + 2Cl2 2NaCl (C) 2Na + 2Cl2 2NaCl (D) Na + Cl2 NaCl | A | All chemical equations, like equations in math, must balance. This means that there must be the same number of each type of atom on both sides of the arrow. Thats because matter is always conserved in a chemical reaction. This is the law of conservation of mass. Look at the equation above for the reaction between carbo... |
Which chemical equation correctly represents the reaction in which carbon combines with oxygen? | (A) C2 + O2 2CO (B) C2 + 2O C2 O2 (C) C + O2 CO2 (D) 2C + O C2 O | C | When scientists write chemical equations, they use chemical symbols and chemical formulas instead of names to represent reactants and products. Look at the chemical reaction illustrated in the Figure 1.1. In this reaction, carbon reacts with oxygen to produce carbon dioxide. Carbon is represented by the chemical symbol... |
What is the missing coefficient in the following chemical equation? ?NO + O2 2NO2 ? | (A) 0 (B) 1 (C) 2 (D) 4 | C | Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction. For example, two molecules of hydrogen would be written as 2H2 . A coefficient of 1 usually isnt written. Co... |
The symbol 2O2 represents two molecules of oxygen. | (A) true (B) false | A | When scientists write chemical equations, they use chemical symbols and chemical formulas instead of names to represent reactants and products. Look at the chemical reaction illustrated in the Figure 1.1. In this reaction, carbon reacts with oxygen to produce carbon dioxide. Carbon is represented by the chemical symbol... |
A coefficient of 1 usually is not written. | (A) true (B) false | A | Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction. For example, two molecules of hydrogen would be written as 2H2 . A coefficient of 1 usually isnt written. Co... |
Subscripts are used to balance chemical equations. | (A) true (B) false | B | Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction. For example, two molecules of hydrogen would be written as 2H2 . A coefficient of 1 usually isnt written. Co... |
The general form of a chemical equation is Reactants = Products. | (A) true (B) false | B | A chemical equation is a shorthand way to sum up what occurs in a chemical reaction. The general form of a chemical equation is: Reactants Products The reactants in a chemical equation are the substances that begin the reaction, and the products are the substances that are produced in the reaction. The reactants are a... |
The first step in balancing a chemical equation is counting atoms. | (A) true (B) false | A | Balancing a chemical equation involves a certain amount of trial and error. In general, however, you should follow these steps: 1. Count each type of atom in reactants and products. Does the same number of each atom appear on both sides of the arrow? If not, the equation is not balanced, and you need to go to step 2. 2... |
A chemical equation must balance only when the reaction reversible. | (A) true (B) false | B | All chemical equations, like equations in math, must balance. This means that there must be the same number of each type of atom on both sides of the arrow. Thats because matter is always conserved in a chemical reaction. This is the law of conservation of mass. Look at the equation above for the reaction between carbo... |
The symbol CO2 represents two molecules of carbon monoxide. | (A) true (B) false | B | When scientists write chemical equations, they use chemical symbols and chemical formulas instead of names to represent reactants and products. Look at the chemical reaction illustrated in the Figure 1.1. In this reaction, carbon reacts with oxygen to produce carbon dioxide. Carbon is represented by the chemical symbol... |
The symbol 2H2 represents two atoms of hydrogen. | (A) true (B) false | B | 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. Therefore, the chemical formula for water is: H2 ... |
Coefficients are used to balance chemical equations. | (A) true (B) false | A | Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction. For example, two molecules of hydrogen would be written as 2H2 . A coefficient of 1 usually isnt written. Co... |
In balancing chemical equations, you should use the smallest subscripts possible. | (A) true (B) false | B | Balancing a chemical equation involves a certain amount of trial and error. In general, however, you should follow these steps: 1. Count the number of each type of atom in reactants and products. Does the same number of each atom appear on both sides of the arrow? If not, the equation is not balanced, and you need to g... |
The number of each type of molecule must be the same on both sides of a chemical equation. | (A) true (B) false | B | All chemical equations, like equations in math, must balance. This means that there must be the same number of each type of atom on both sides of the arrow. Thats because matter is always conserved in a chemical reaction. This is the law of conservation of mass. Look at the equation above for the reaction between carbo... |
Changing coefficients changes the substances involved in a chemical reaction. | (A) true (B) false | B | 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 elements or compounds. A chemical reaction can be represented by thi... |
Chemists use a standard method to represent chemical reactions. | (A) true (B) false | A | A chemical equation is a symbolic representation of a chemical reaction. It is a shorthand way of showing how atoms are rearranged in the reaction. The general form of a chemical equation was introduced in this chapters lesson "Introduction to Chemical Reactions." It is: Reactants ! Products Consider the simple example... |
The chemical equation H2 CO3 H2 O + CO2 is balanced. | (A) true (B) false | A | All chemical equations, like equations in math, must balance. This means that there must be the same number of each type of atom on both sides of the arrow. Thats because matter is always conserved in a chemical reaction. This is the law of conservation of mass. Look at the equation above for the reaction between carbo... |
Water is the reactant in the chemical equation H2 O H2 + O2 . | (A) true (B) false | A | Some chemical equations are more challenging to write. Consider the reaction in which hydrogen (H2 ) and oxygen (O2 ) combine to form water (H2 O). Hydrogen and oxygen are the reactants, and water is the product. To write a chemical equation for this reaction, you would start by writing symbols for the reactants and pr... |
symbolic representation of a chemical reaction | (A) chemical symbol (B) coefficient (C) H2 (D) chemical equation (E) 2H (F) subscript (G) chemical formula | D | A chemical equation is a symbolic representation of a chemical reaction. It is a shorthand way of showing how atoms are rearranged in the reaction. The general form of a chemical equation was introduced in this chapters lesson "Introduction to Chemical Reactions." It is: Reactants ! Products Consider the simple example... |
example of a coefficient | (A) chemical symbol (B) coefficient (C) H2 (D) chemical equation (E) 2H (F) subscript (G) chemical formula | E | Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction. For example, two molecules of hydrogen would be written as 2H2 . A coefficient of 1 usually isnt written. Co... |
symbol of a chemical compound | (A) chemical symbol (B) coefficient (C) H2 (D) chemical equation (E) 2H (F) subscript (G) chemical formula | G | Elements are represented by chemical symbols. Examples are H for hydrogen and O for oxygen. Compounds are represented by chemical formulas. Youve already seen the chemical formula for water. Its H2 O. The subscript 2 after the H shows that there are two atoms of hydrogen in a molecule of water. The O for oxygen has no ... |
example of a subscript | (A) chemical symbol (B) coefficient (C) H2 (D) chemical equation (E) 2H (F) subscript (G) chemical formula | C | 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. Therefore, the chemical formula for water is: H2 ... |
number showing how many atoms or molecules of a given element or compound are involved in a chemical | (A) chemical symbol (B) coefficient (C) H2 (D) chemical equation (E) 2H (F) subscript (G) chemical formula | B | 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. Therefore, the chemical formula for water is: H2 ... |
symbol of an chemical element | (A) chemical symbol (B) coefficient (C) H2 (D) chemical equation (E) 2H (F) subscript (G) chemical formula | A | In the Figure 1.1, each element is represented by its chemical symbol, which consists of one or two letters. The first letter of the symbol is always written in upper case, and the second letterif there is oneis always written in lower case. For example, the symbol for copper is Cu. It stands for cuprum, which is the L... |
number showing how many atoms of a given element are in a molecule | (A) chemical symbol (B) coefficient (C) H2 (D) chemical equation (E) 2H (F) subscript (G) chemical formula | F | Elements are represented by chemical symbols. Examples are H for hydrogen and O for oxygen. Compounds are represented by chemical formulas. Youve already seen the chemical formula for water. Its H2 O. The subscript 2 after the H shows that there are two atoms of hydrogen in a molecule of water. The O for oxygen has no ... |
one reactant breaking down into two or more products | (A) synthesis reaction (B) combustion reaction (C) decomposition reaction (D) single replacement reaction (E) double replacement reaction (F) burning (G) fuel | C | A decomposition reaction is the reverse of a synthesis reaction. In a decomposition reaction, one reactant breaks down into two or more products. This can be represented by the general equation: AB ! A + B Two examples of decomposition reactions are described below. You can see other examples at this URL: http://w |
The general equation for a synthesis reaction is | (A) AB A + B (B) A + BC B + AC (C) A+BC (D) AB + C A + BC | C | A synthesis reaction occurs when two or more reactants combine to form a single product. A synthesis reaction can be represented by the general equation: A+BC In this equation, the letters A and B represent the reactants that begin the reaction, and the letter C represents the product that is synthesized in the reactio... |
ions changing places in two compounds | (A) synthesis reaction (B) combustion reaction (C) decomposition reaction (D) single replacement reaction (E) double replacement reaction (F) burning (G) fuel | E | Replacement reactions involve ions. They occur when ions switch places in compounds. There are two types of replacement reactions: single and double. Both types are described below. |
Which of the following is a decomposition reaction? | (A) 2Na + Cl2 2NaCl (B) 2H2 O 2H2 + O2 (C) CH4 + O2 CO2 + H2 O (D) NaCl + AgF NaF + AgCl | B | A decomposition reaction is the reverse of a synthesis reaction. In a decomposition reaction, one reactant breaks down into two or more products. This can be represented by the general equation: AB ! A + B Two examples of decomposition reactions are described below. You can see other examples at this URL: http://w |
two reactants combining to form a single product | (A) synthesis reaction (B) combustion reaction (C) decomposition reaction (D) single replacement reaction (E) double replacement reaction (F) burning (G) fuel | A | A synthesis reaction occurs when two or more reactants combine to form a single product. A synthesis reaction can be represented by the general equation: A+B !C In this general equation (and others like it in this lesson), the letters A, B,C, and so on represent atoms or ions of elements. The arrow shows the direction ... |
Which type of reaction is represented by the following chemical equation? 2K + 2H2 O 2KOH + H2 | (A) double replacement (B) single replacement (C) decomposition (D) synthesis | B | A single replacement reaction occurs when one ion takes the place of another in a single compound. This type of reaction has the general equation: A + BC ! B + AC Do you see how A has replaced B in the compound? The compound BC has become the compound AC. An example of a single replacement reaction occurs when potassiu... |
Which of the following is always a product of a combustion reaction? | (A) water (B) ashes (C) smoke (D) oxygen | A | 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 gives off heat and light as well. The general equation for a... |
substance reacting quickly with oxygen | (A) synthesis reaction (B) combustion reaction (C) decomposition reaction (D) single replacement reaction (E) double replacement reaction (F) burning (G) fuel | B | A combustion reaction occurs when a substance reacts quickly with oxygen (O2 ). You can see an example of a combustion reaction in Figure 8.10. Combustion is commonly called burning. The substance that burns is usually referred to as fuel. The products of a combustion reaction include carbon dioxide (CO2 ) and water (H... |
one of the reactants in a combustion reaction | (A) synthesis reaction (B) combustion reaction (C) decomposition reaction (D) single replacement reaction (E) double replacement reaction (F) burning (G) fuel | G | 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 gives off heat and light as well. The general equation for a... |
In living cells, energy is produced by the process called | (A) photosynthesis (B) sugar synthesis (C) cellular respiration (D) glucose decomposition | C | Cellular respiration is the process of extracting energy in the form of ATP from the glucose in the food you eat. How does cellular respiration happen inside of the cell? Cellular respiration is a three step process. Briefly: 1. In stage one, glucose is broken down in the cytoplasm of the cell in a process called glyco... |
one ion taking the place of another in a compound | (A) synthesis reaction (B) combustion reaction (C) decomposition reaction (D) single replacement reaction (E) double replacement reaction (F) burning (G) fuel | D | Replacement reactions involve ions. They occur when ions switch places in compounds. There are two types of replacement reactions: single and double. Both types are described below. |
another term for a combustion reaction | (A) synthesis reaction (B) combustion reaction (C) decomposition reaction (D) single replacement reaction (E) double replacement reaction (F) burning (G) fuel | F | A combustion reaction occurs when a substance reacts quickly with oxygen (O2 ). You can see an example of a combustion reaction in Figure 8.10. Combustion is commonly called burning. The substance that burns is usually referred to as fuel. The products of a combustion reaction include carbon dioxide (CO2 ) and water (H... |
Which of the following is an example of a synthesis reaction? | (A) 2NO + O2 2NO2 (B) 2Na + Cl2 2NaCl2 (C) H2 O H2 + O2 (D) two of the above | D | A synthesis reaction occurs when two or more reactants combine to form a single product. A synthesis reaction can be represented by the general equation: A+B !C In this general equation (and others like it in this lesson), the letters A, B,C, and so on represent atoms or ions of elements. The arrow shows the direction ... |
A decomposition reaction is represented by the general equation | (A) A + B + C AB + C (B) A + BC AB + C (C) AB A + B (D) none of the above | C | 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 of the reaction. The arrow shows the direction in which the reaction... |
Which type of reaction is represented by the following chemical equation? NaCl + AgF NaF + AgCl | (A) synthesis (B) decomposition (C) single replacement (D) double replacement | D | An example of a synthesis reaction is the combination of sodium (Na) and chlorine (Cl) to produce sodium chloride (NaCl). This reaction is represented by the chemical equation: 2Na + Cl2 ! 2NaCl Sodium is a highly reactive metal, and chlorine is a poisonous gas (see Figure 8.6). The compound they synthesize has very di... |
A synthesis reaction occurs when two or more reactants combine to form a single product. | (A) true (B) false | A | A synthesis reaction occurs when two or more reactants combine to form a single product. A synthesis reaction can be represented by the general equation: A+B !C In this general equation (and others like it in this lesson), the letters A, B,C, and so on represent atoms or ions of elements. The arrow shows the direction ... |
Which of the following is always a reactant in a combustion reaction? | (A) water (B) oxygen (C) carbon dioxide (D) two of the above | B | 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 gives off heat and light as well. The general equation for a... |
Another term for a combustion reaction is decomposition. | (A) true (B) false | B | A decomposition reaction is the reverse of a synthesis reaction. In a decomposition reaction, one reactant breaks down into two or more products. This can be represented by the general equation: AB ! A + B Two examples of decomposition reactions are described below. You can see other examples at this URL: http://w |
Methane is a | (A) hydrocarbon (B) component of natural gas (C) compound containing only carbon and hydrogen (D) all of the above | D | Natural gas is mostly methane. |
What do living cells use for fuel? | (A) oxygen (B) water (C) glucose (D) hydrocarbons | C | Chemical energy that organisms need comes from food. The nearly universal food for life is the sugar glucose. Glucose is a simple carbohydrate with the chemical formula C6 H12 O6 . The glucose molecule stores chemical energy in a concentrated, stable form. In your body, glucose is the form of energy that is carried in ... |
Fossil fuels such as oil and natural gas consist of hydrocarbons. | (A) true (B) false | A | Fossil fuels are made from plants and animals that lived hundreds of millions of years ago. The plants and animals died. Their remains settled onto the ground and at the bottom of the sea. Layer upon layer of organic material was laid down. Eventually, the layers were buried very deeply. They experienced intense heat a... |
The reaction in which carbon dioxide and water combine to form glucose | (A) is a combustion reaction (B) is called photosynthesis (C) takes place in all living cells (D) all of the above | B | Some of the most important biochemical reactions are the reactions involved in photosynthesis and cellular respira- tion. Together, these two processes provide energy to almost all of Earths organisms. The two processes are closely related, as you can see in the Figure 1.1. In photosynthesis, light energy from the sun ... |
The fuel that cells use for energy is oxygen. | (A) true (B) false | B | What goes into the cell? Oxygen and glucose are both reactants of cellular respiration. Oxygen enters the body when an organism breathes. Glucose enters the body when an organism eats. |
Plants combine carbon dioxide and water to form glucose. | (A) true (B) false | A | What is the source of glucose for living things? It is made by plants and certain other organisms. The process in which glucose is made using energy in light is photosynthesis. This process requires carbon dioxide and water. It produces oxygen in addition to glucose. Photosynthesis consists of many chemical reactions. ... |
Water decomposes when an electric current passes through it. | (A) true (B) false | A | Another example of a decomposition reaction is illustrated in Figure 8.9. Water (H2 O) decomposes to hydrogen (H2 ) and oxygen (O2 ) when an electric current passes through it. This reaction is represented by the equation: 2H2 O ! 2H2 + O2 What is the reverse of this decomposition reaction? (Hint: How is water synthesi... |
A combustion reaction usually gives off heat and light. | (A) true (B) false | A | All combustion reactions are exothermic reactions. During a combustion reaction, a substance burns as it combines with oxygen. When substances burn, they usually give off energy as heat and light. Look at the big bonfire in the Figure 1.2. The combustion of wood is an exothermic reaction that releases a lot of energy a... |
The burning of glucose in cells is called cellular combustion. | (A) true (B) false | B | Your own body cells burn fuel in combustion reactions. The fuel is glucose (C6 H12 O6 ), a simple sugar. The process in which combustion of glucose occurs in body cells is called cellular respiration. This combustion reaction provides energy for life processes. Cellular respiration can be summed up by the equation: C6 ... |
Sodium chloride forms in a decomposition reaction. | (A) true (B) false | B | An example of a synthesis reaction is the combination of sodium (Na) and chlorine (Cl) to produce sodium chloride (NaCl). This reaction is represented by the chemical equation: 2Na + Cl2 ! 2NaCl Sodium is a highly reactive metal, and chlorine is a poisonous gas (see Figure 8.6). The compound they synthesize has very di... |
Methane and oxygen combine in a synthesis reaction. | (A) true (B) false | B | 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, methane (CH4 ) combines with oxygen (O2 ) in the air and produces carbon dioxide (CO2 ) and wate... |
One product of the reaction in question 5 is carbon dioxide. | (A) true (B) false | A | The short term cycling of carbon begins with carbon dioxide (CO2 ) in the atmosphere. |
There are two types of decomposition reactions. | (A) true (B) false | B | A decomposition reaction is the reverse of a synthesis reaction. In a decomposition reaction, one reactant breaks down into two or more products. This can be represented by the general equation: AB ! A + B Two examples of decomposition reactions are described below. You can see other examples at this URL: http://w |
Carbon dioxide forms only in combustion reactions. | (A) true (B) false | B | The short term cycling of carbon begins with carbon dioxide (CO2 ) in the atmosphere. |
The general equation AB + CD AD + CB represents a replacement reaction. | (A) true (B) false | A | A double replacement reaction occurs when two compounds exchange ions. This produces two new compounds. A double replacement reaction can be represented by the general equation: AB +CD ! AD +CB Do you see how B and D have changed places? Both reactant compounds have changed. An example of a double replacement reaction ... |
The chemical reaction 2K + 2H2 O 2KOH + H2 is a replacement reaction. | (A) true (B) false | A | A single replacement reaction occurs when one ion takes the place of another in a single compound. This type of reaction has the general equation: A + BC ! B + AC Do you see how A has replaced B in the compound? The compound BC has become the compound AC. An example of a single replacement reaction occurs when potassiu... |
Which statement describes a role of energy in chemical reactions? | (A) Energy is created in exothermic reactions (B) Energy is always released in chemical reactions (C) Energy is needed for chemical reactions to start (D) Energy is destroyed in endothermic reactions | C | All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. In some chemical reactions, called exothermic reactions, more energy is released when new bonds form in the products than is needed to break bonds in the reactants. The opposite is ... |
All chemical reactions need energy to | (A) form bonds in products (B) break bonds in reactants (C) get started (D) two of the above | D | Chemical reactions also need energy to be activated. They require a certain amount of energy just to get started. This energy is called activation energy. For example, activation energy is needed to start a car engine. Turning the key causes a spark that activates the burning of gasoline in the engine. The combustion o... |
The energy needed for photosynthesis is in the form of | (A) glucose (B) oxygen (C) light (D) heat | C | Most of the energy used by living things comes either directly or indirectly from the sun. Thats because sunlight provides the energy for photosynthesis. This is the process in which plants and certain other organisms synthesize glucose (C6 H12 O6 ). The process uses carbon dioxide and water and also produces oxygen. T... |
Which statement about exothermic reactions is false? | (A) They need activation energy (B) They include combustion (C) They give off energy (D) They take in heat | D | All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. In some chemical reactions, called exothermic reactions, more energy is released when new bonds form in the products than is needed to break bonds in the reactants. The opposite is ... |
When products have less chemical energy than reactants, a chemical reaction | (A) is endothermic (B) is exothermic (C) absorbs energy (D) two of the above | B | 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 bonds in reactants than is released when bonds form in products. These reactions, cal... |
A constant input of energy is needed in | (A) exothermic reactions (B) endothermic reactions (C) all chemical reactions (D) none of the above | B | Energy provides the ability to move or change matter from one state to another (for example, from solid to liquid). Every living thing needs energy to live and grow. Your body gets its energy from food, but that is only a small part of the energy you use every day. Cooking your food takes energy, and so does keeping it... |
You can increase the rate of a chemical reaction by | (A) increasing the temperature of reactants (B) decreasing the surface area of reactants (C) decreasing the concentration of reactants (D) all of the above | A | When the temperature of reactants is higher, the rate of the reaction is faster. At higher temperatures, particles of reactants have more energy, so they move faster. They are more likely to bump into one another and to collide with greater force. For example, when you fry an egg, turning up the heat causes the egg to ... |
According to the law of conservation of energy, energy | (A) cannot be created (B) cannot be destroyed (C) cannot change form (D) two of the above | D | Energy changes form when something happens. But the total amount of energy always stays the same. The Law of Conservation of Energy says that energy cannot be created or destroyed. Scientists observed that energy could change from one form to another. They also observed that the overall amount of energy did not change.... |
Factors that affect reaction rates include | (A) temperature (B) concentration (C) surface area (D) all of the above | D | 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. |
A catalyst | (A) can catalyze just one chemical reaction (B) is always changed in a chemical reaction (C) becomes a product in a chemical reaction (D) helps reactants come together in a chemical reaction | D | Some reactions need extra help to occur quickly. They need another substance, called a catalyst. A catalyst is a substance that increases the rate of a chemical reaction but is not changed or used up in the reaction. The catalyst can go on to catalyze many more reactions. Catalysts are not reactants, but they help reac... |
Crushing a solid reactant into a powder will | (A) decrease the reactants surface area (B) increase the rate of the reaction (C) decrease the concentration of products (D) increase the temperature of reactants | B | When a solid substance is involved in a chemical reaction, only the matter at the surface of the solid is exposed to other reactants. If a solid has more surface area, more of it is exposed and able to react. Therefore, increasing the surface area of solid reactants increases the reaction rate. For example, crushing a ... |
Which statement about catalysts is true? | (A) They change the rate of chemical reactions (B) They are reactants in chemical reactions (C) They are used up in chemical reactions (D) two of the above | A | Catalysts interact with reactants so the reaction can occur by an alternate pathway that has a lower activation energy. Activation energy is the energy needed to start a reaction. When activation energy is lower, more reactant particles have enough energy to react so the reaction goes faster. Many catalysts work like t... |
energy stored in chemical bonds | (A) activation energy (B) catalyst (C) concentration (D) endothermic (E) exothermic (F) reaction rate (G) chemical energy | G | Energy is stored in the bonds between atoms that make up compounds. This energy is called chemical energy, and it is a form of potential energy. If the bonds between atoms are broken, the energy is released and can do work. The wood in the fireplace in Figure 17.10 has chemical energy. The energy is released as thermal... |
substance that speeds up chemical reactions | (A) activation energy (B) catalyst (C) concentration (D) endothermic (E) exothermic (F) reaction rate (G) chemical energy | B | Some reactions need extra help to occur quickly. They need another substance called a catalyst. A catalyst is a substance that increases the rate of a chemical reaction. A catalyst isnt a reactant, so it isnt changed or used up in the reaction. Therefore, it can catalyze many other reactions. |
turning out heat | (A) activation energy (B) catalyst (C) concentration (D) endothermic (E) exothermic (F) reaction rate (G) chemical energy | E | A warm-air heating system uses thermal energy to heat air. It then forces the warm air through a system of ducts. You can see a diagram of this type of heating system in Figure 18.13. Typically, the air is heated in a furnace that burns natural gas or heating oil. When the air is warm, a fan blows it through the ducts ... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.