compounds mixtures

What is a molecule?

• A) A single atom

• B) A group of two or more atoms held together by chemical bonds

• C) A mixture of atoms and compounds

• D) A single element

Which of the following is an example of a molecule but not a compound?

• A) Water (H2O)

• B) Carbon dioxide (CO2)

• C) Oxygen (O2)

• D) Sodium chloride (NaCl)

What defines a compound?

• A) A group of identical atoms

• B) A substance containing two or more different elements chemically bonded together

• C) A mixture of substances

• D) A substance that cannot be separated by physical means

Which of the following is NOT a compound?

• A) Water (H2O)

• B) Carbon dioxide (CO2)

• C) Nitrogen (N2)

• D) Sulfuric acid (H2SO4)

What does the subscript “2” in the chemical formula H2O signify?

• A) There are two molecules of hydrogen.

• B) There are two hydrogen atoms in the molecule.

• C) There are two oxygen atoms in the molecule.

• D) There are two molecules of water.

Which type of bond forms large structures instead of molecules?

• A) Covalent bonds

• B) Hydrogen bonds

• C) Ionic bonds

• D) Metallic bonds

What does the formula NaCl represent?

• A) A molecule of sodium and chlorine

• B) A ratio of one sodium ion to one chloride ion in a large structure

• C) A mixture of sodium and chlorine atoms

• D) A gas made of sodium and chlorine

What is a mixture?

• A) A combination of elements that are chemically bonded

• B) A substance made of two or more elements in fixed proportions

• C) A physical combination of different substances that are not chemically bonded

• D) A substance that cannot be separated by physical methods

Which of the following would be classified as a mixture?

• A) Water (H2O)

• B) Sodium chloride (NaCl)

• C) Air (containing oxygen, nitrogen, carbon dioxide, etc.)

• D) Sulfuric acid (H2SO4)

How can the components of a mixture be separated?

• A) By chemical reactions

• B) By nuclear reactions

• C) By physical methods like filtration, crystallization, or distillation

• D) By breaking chemical bonds