Gr 8 Natural Sciences Ch 2.1: Pure substances

What is true about the properties of elements in a compound?

The properties are the same as the individual elements
The properties are different from the individual elements (correct)
The properties are only slightly different from the individual elements
The properties are similar to the individual elements, but with a slight change

Which type of molecule is composed of different kinds of atoms?

O2 (oxygen)
N2 (nitrogen)
H2O (water) (correct)
CO (carbon monoxide)

What holds atoms together in a molecule?

Gravitational forces
Chemical bonds (correct)
Electromagnetic forces
Nuclear forces

What is represented by a chemical formula?

The types and numbers of atoms in a molecule (B) Signup and view all the answers

What occurs in a decomposition reaction?

A single compound breaks down into two or more simpler substances (C) Signup and view all the answers

What is the result of the decomposition of water?

Hydrogen gas and oxygen gas (D) Signup and view all the answers

What is the chemical equation for the decomposition of water?

2H2O → 2H2 + O2 (B) Signup and view all the answers

What occurs in a chemical reaction?

The breaking of chemical bonds and the formation of new chemical bonds (D) Signup and view all the answers

What is a pure substance?

A material made of only one kind of matter (C) Signup and view all the answers

What is a compound?

A substance made up of two or more different kinds of atoms chemically bonded together (D) Signup and view all the answers

What is the difference between an element and a compound?

An element is made up of one kind of atom, while a compound is made up of two or more different kinds of atoms (A) Signup and view all the answers

What is the chemical formula for water?

H2O (D) Signup and view all the answers

What is the chemical formula for carbon dioxide?

CO2 (D) Signup and view all the answers

What is an example of an element?

Copper (Cu) (D) Signup and view all the answers

What is an example of a compound?

Water (H2O) (A) Signup and view all the answers

What is the term for the force that holds atoms together in a molecule?

Chemical Bond (A) Signup and view all the answers

What is the primary reason for the difference in properties between a compound and its constituent elements?

The formation of chemical bonds (A) Signup and view all the answers

What is the result of the breaking of chemical bonds in a chemical reaction?

The formation of simpler substances (D) Signup and view all the answers

What is the purpose of a chemical formula?

To indicate the types and numbers of atoms in a molecule (A) Signup and view all the answers

What is the difference between molecules composed of same kind of atoms and those composed of different kinds of atoms?

Their properties (D) Signup and view all the answers

What is the role of protons and electrons in the formation of chemical bonds?

They attract each other (B) Signup and view all the answers

What is the result of the formation of new chemical bonds in a chemical reaction?

The formation of new substances (D) Signup and view all the answers

What is the characteristic of a molecule composed of oxygen and hydrogen atoms?

It is a liquid at room temperature (A) Signup and view all the answers

What is the role of a chemical equation in a chemical reaction?

It represents the chemical reaction (B) Signup and view all the answers

What is a characteristic of elements?

They exist as individual atoms or molecules made up of the same type of atoms (A) Signup and view all the answers

Which of the following is an example of a pure substance?

Copper (C) Signup and view all the answers

What is the main difference between elements and compounds?

Elements consist of only one kind of atom, while compounds consist of two or more kinds of atoms (B) Signup and view all the answers

What is the term for a group of two or more atoms bonded together?

Molecule (B) Signup and view all the answers

Which of the following substances consists of only one kind of atom?

Copper (C) Signup and view all the answers

What is a characteristic of compounds?

They have a fixed ratio of atoms (D) Signup and view all the answers

What is the fixed ratio of atoms in a compound?

Fixed (C) Signup and view all the answers

What is true about the atoms in a molecule of oxygen?

They are chemically bonded (D) Signup and view all the answers

What is the primary reason for the difference in properties between a compound and its constituent elements?

The formation of new chemical bonds (D) Signup and view all the answers

Which of the following statements is true about molecules?

Molecules can be composed of same kind of atoms or different kinds of atoms (B) Signup and view all the answers

What is the role of chemical formulae in chemistry?

To represent the types and numbers of atoms in a molecule (A) Signup and view all the answers

What is the result of the breaking of chemical bonds in a chemical reaction?

The decomposition of the reactant (A) Signup and view all the answers

What is the purpose of a chemical equation?

To represent the chemical reaction (C) Signup and view all the answers

What is the result of the formation of new chemical bonds in a chemical reaction?

The formation of new substances (C) Signup and view all the answers

What is the characteristic of a molecule composed of oxygen and hydrogen atoms?

It is a compound (B) Signup and view all the answers

What is the role of protons and electrons in the formation of chemical bonds?

Protons attract electrons (D) Signup and view all the answers

What is unique about the properties of an element?

They are fixed and distinct from those of its compounds. (B) Signup and view all the answers

Why do elements exist as individual atoms or molecules?

Because they are made up of only one kind of atom. (A) Signup and view all the answers

What is the relationship between the atoms in a compound?

They are chemically bonded in a fixed ratio. (C) Signup and view all the answers

What is the main difference between the molecules of oxygen and carbon dioxide?

The type of atoms in each molecule. (D) Signup and view all the answers

What is a characteristic of the atoms in a molecule of a compound?

They are of different kinds. (D) Signup and view all the answers

What is a result of the chemical bonds between atoms in a molecule?

A change in the properties of the individual atoms. (C) Signup and view all the answers

What is the purpose of a chemical formula in a compound?

To represent the ratio of atoms in a molecule. (D) Signup and view all the answers

What is the difference between an element and a compound in terms of their chemical bonds?

Elements have chemical bonds between same kind of atoms, while compounds have chemical bonds between different kinds of atoms. (D) Signup and view all the answers

What is the primary characteristic of an element?

It consists of only one kind of atom. (D) Signup and view all the answers

What is the main difference between an element and a compound?

The type of atoms that make them up. (A) Signup and view all the answers

What is the role of chemical bonds in a molecule?

They hold the atoms together in a molecule. (C) Signup and view all the answers

What is the fixed ratio of atoms in a compound?

Fixed and dependent on the type of atoms. (C) Signup and view all the answers

What is the result of the decomposition of a compound?

A simpler substance is formed. (D) Signup and view all the answers

What is the characteristic of molecules composed of the same kind of atoms?

They are elements. (D) Signup and view all the answers

What is the importance of understanding the difference between elements and compounds?

It is essential for studying chemistry. (B) Signup and view all the answers

What is the main difference between the properties of a compound and its constituent elements?

The compound's properties are different from the individual elements. (D) Signup and view all the answers

Which of the following molecules is composed of only two atoms?

O2 (A) Signup and view all the answers

What is the primary role of chemical bonds in a molecule?

To hold atoms together. (D) Signup and view all the answers

What is the result of the decomposition of H2O?

2H2 + O2 (A) Signup and view all the answers

What is the purpose of a chemical formula?

To indicate the type and number of atoms in a molecule. (B) Signup and view all the answers

What occurs during the formation of new chemical bonds in a chemical reaction?

Atoms are rearranged to form new substances. (A) Signup and view all the answers

What is the role of protons and electrons in the formation of chemical bonds?

The attraction between protons and electrons forms bonds. (D) Signup and view all the answers

What is a characteristic of a molecule composed of different kinds of atoms?

It is always a compound. (B) Signup and view all the answers

Gr 8 Natural Sciences Ch 2.1: Pure substances

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Questions and Answers

What is true about the properties of elements in a compound?

Which type of molecule is composed of different kinds of atoms?

What holds atoms together in a molecule?

What is represented by a chemical formula?

What occurs in a decomposition reaction?

What is the result of the decomposition of water?

What is the chemical equation for the decomposition of water?

What occurs in a chemical reaction?

What is a pure substance?

What is a compound?

What is the difference between an element and a compound?

What is the chemical formula for water?

What is the chemical formula for carbon dioxide?

What is an example of an element?

What is an example of a compound?

What is the term for the force that holds atoms together in a molecule?

What is the primary reason for the difference in properties between a compound and its constituent elements?

What is the result of the breaking of chemical bonds in a chemical reaction?

What is the purpose of a chemical formula?

What is the difference between molecules composed of same kind of atoms and those composed of different kinds of atoms?

What is the role of protons and electrons in the formation of chemical bonds?

What is the result of the formation of new chemical bonds in a chemical reaction?

What is the characteristic of a molecule composed of oxygen and hydrogen atoms?

What is the role of a chemical equation in a chemical reaction?

What is a characteristic of elements?

Which of the following is an example of a pure substance?

What is the main difference between elements and compounds?

What is the term for a group of two or more atoms bonded together?

Which of the following substances consists of only one kind of atom?

What is a characteristic of compounds?

What is the fixed ratio of atoms in a compound?

What is true about the atoms in a molecule of oxygen?

What is the primary reason for the difference in properties between a compound and its constituent elements?

Which of the following statements is true about molecules?

What is the role of chemical formulae in chemistry?

What is the result of the breaking of chemical bonds in a chemical reaction?

What is the purpose of a chemical equation?

What is the result of the formation of new chemical bonds in a chemical reaction?

What is the characteristic of a molecule composed of oxygen and hydrogen atoms?

What is the role of protons and electrons in the formation of chemical bonds?

What is unique about the properties of an element?

Why do elements exist as individual atoms or molecules?

What is the relationship between the atoms in a compound?

What is the main difference between the molecules of oxygen and carbon dioxide?

What is a characteristic of the atoms in a molecule of a compound?

What is a result of the chemical bonds between atoms in a molecule?

What is the purpose of a chemical formula in a compound?

What is the difference between an element and a compound in terms of their chemical bonds?

What is the primary characteristic of an element?

What is the main difference between an element and a compound?

What is the role of chemical bonds in a molecule?

What is the fixed ratio of atoms in a compound?

What is the result of the decomposition of a compound?

What is the characteristic of molecules composed of the same kind of atoms?

What is the importance of understanding the difference between elements and compounds?

What is the main difference between the properties of a compound and its constituent elements?

Which of the following molecules is composed of only two atoms?

What is the primary role of chemical bonds in a molecule?

What is the result of the decomposition of H2O?

What is the purpose of a chemical formula?

What occurs during the formation of new chemical bonds in a chemical reaction?

What is the role of protons and electrons in the formation of chemical bonds?

What is a characteristic of a molecule composed of different kinds of atoms?

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