This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). The model contains 1 carbon atom (identified by black color or labeled C) bonded to 4 hydrogen atoms (small white or labeled H), giving the formula CH₄ with 5 atoms total per molecule—the specific number and types of atoms determine the molecule's identity and properties. Choice A is correct because it accurately describes which atoms are bonded to which in the arrangement, with the central C connected to all four H atoms. Choice B incorrectly counts 2 hydrogen atoms when the model clearly shows 4, making an atom counting error—carefully counting each atom type separately is essential for determining molecular composition. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). For water H₂O: In the model shown, there are 2 hydrogen atoms (smaller circles, often white or labeled H) bonded to 1 oxygen atom (larger circle, often red or labeled O), giving a total of 3 atoms per water molecule. The bonds are shown as lines connecting each hydrogen to the central oxygen, and the bent arrangement is characteristic of water—this composition of 2 H and 1 O defines water at the molecular level. Choice B is correct because it accurately counts the atoms shown: 2 H and 1 O, giving the right chemical formula with proper subscripts matching the atom count. Choice C incorrectly counts 3 hydrogen atoms when the model clearly shows 2, making an atom counting error—carefully counting each atom type separately is essential for determining molecular composition. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). For CO₂: The diagram shows 1 carbon atom (often black or labeled C) in the center bonded to 2 oxygen atoms (often red or labeled O) on either side in a linear arrangement, giving the formula CO₂ with total of 3 atoms per molecule—this is carbon dioxide, the gas we exhale and that plants use for photosynthesis. Choice B is correct because it accurately describes which atoms are bonded to which in the arrangement, with the central C connected to both O atoms. Choice A treats the molecule as separated individual atoms rather than a bonded group, missing that the lines connecting atoms represent chemical bonds—a molecule is specifically a group of atoms bonded together, not loose atoms floating near each other. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). The model contains 1 nitrogen atom (identified by blue color or labeled N) bonded to 3 hydrogen atoms (small white or labeled H), giving the formula NH₃ with 4 atoms total per molecule—the specific number and types of atoms determine the molecule's identity and properties. Choice B is correct because it correctly identifies all element types present in the model: nitrogen and hydrogen. Choice A incorrectly counts only 1 kind of atom when the model clearly shows 2 (N and H), making an atom counting error—carefully counting each atom type separately is essential for determining molecular composition. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). For CO₂: The diagram shows 1 carbon atom (often black or labeled C) in the center bonded to 2 oxygen atoms (often red or labeled O) on either side in a linear arrangement, giving the formula CO₂ with total of 3 atoms per molecule—this is carbon dioxide, the gas we exhale and that plants use for photosynthesis. Choice B is correct because it correctly identifies all element types present in the model: carbon and oxygen. Choice C confuses the element types, identifying the oxygen atoms as hydrogen, when the color coding shows red = oxygen and labeling clearly indicates which atom is which. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). The model contains 1 carbon atom (identified by black color or labeled C) bonded to 4 hydrogen atoms (small white or labeled H), giving the formula CH₄ with 5 atoms total per molecule—the specific number and types of atoms determine the molecule's identity and properties. Choice A is correct because it gives the right chemical formula with proper subscripts matching the atom count: 1 C and 4 H. Choice B gives the formula C₂H₄ with incorrect subscripts, when counting the atoms in the model shows 1 C and 4 H which corresponds to formula CH₄. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). For water H₂O: In the model shown, there are 2 hydrogen atoms (smaller circles, often white or labeled H) bonded to 1 oxygen atom (larger circle, often red or labeled O), giving a total of 3 atoms per water molecule. The bonds are shown as lines connecting each hydrogen to the central oxygen, and the bent arrangement is characteristic of water—this composition of 2 H and 1 O defines water at the molecular level. Choice A is correct because it accurately counts the atoms shown: 1 O per molecule, focusing on just one molecule as specified. Choice B incorrectly counts atoms from multiple molecules instead of one, leading to wrong total. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). The model contains 1 nitrogen atom (identified by blue color or labeled N) bonded to 3 hydrogen atoms (small white or labeled H), giving the formula NH₃ with 4 atoms total per molecule—the specific number and types of atoms determine the molecule's identity and properties. Choice C is correct because it gives the right chemical formula with proper subscripts matching the atom count: 1 N and 3 H. Choice A gives the formula NH₂ with incorrect subscripts, when counting the atoms in the model shows 1 N and 3 H which corresponds to formula NH₃. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). For methane CH₄: The model contains 1 carbon atom (black or labeled C) bonded to 4 hydrogen atoms (white or labeled H), giving the formula CH₄ with 5 atoms total per molecule—the specific number and types of atoms determine the molecule's identity and properties. Choice C is correct because it gives the right chemical formula with proper subscripts matching the atom count: 1 C and 4 H. Choice A incorrectly gives the formula CH₃ with incorrect subscripts, when counting the atoms in the model shows 1 C and 4 H which corresponds to formula CH₄. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).

This question tests understanding of how to use particle-level models to represent molecules, which are groups of atoms bonded together. A molecule is formed when two or more atoms chemically bond together in a specific arrangement—each type of atom is represented by its element symbol (H for hydrogen, O for oxygen, C for carbon, N for nitrogen), and the chemical formula uses subscripts to show how many atoms of each type are in one molecule (for example, H₂O means 2 hydrogen atoms bonded to 1 oxygen atom, while CO₂ means 1 carbon atom bonded to 2 oxygen atoms). For water H₂O: In the model shown, there are 2 hydrogen atoms (smaller circles, often white or labeled H) bonded to 1 oxygen atom (larger circle, often red or labeled O), giving a total of 3 atoms per water molecule. The bonds are shown as lines connecting each hydrogen to the central oxygen, and the bent arrangement is characteristic of water—this composition of 2 H and 1 O defines water at the molecular level. Choice B is correct because it accurately counts the atoms shown: 2 H and 1 O, giving the right chemical formula with proper subscripts matching the atom count. Choice A incorrectly gives the formula HO₂ with incorrect subscripts, when counting the atoms in the model shows 2 H and 1 O which corresponds to formula H₂O. To interpret molecular models: (1) identify each atom type by its label, color, or size (H = small/white, O = larger/red, C = black, N = blue typically), (2) count how many atoms of each type are present in one molecule, (3) write the formula with subscripts showing the count (2 H atoms = H₂, 1 O atom = O, giving H₂O), (4) verify bonds connect atoms (lines between circles), and (5) remember that each molecule is a discrete unit—if diagram shows 3 water molecules, count atoms in just one to get H₂O, not all combined. Common mistakes: (a) counting atoms from multiple molecules instead of one, (b) confusing atom types (check labels/colors carefully), (c) writing formulas with wrong subscripts (count carefully: 2 H means H₂ not H2), (d) forgetting atoms without subscripts (H₂O has 1 oxygen even though no subscript after O), and (e) counting bonds as atoms (4 bonds doesn't mean 4 atoms necessarily).