Question

1. which of the following is not a true statement?

a. two or more atoms held together with bonds make up a molecule.
b. pure substances are made of only one type of atom.
c. at least two types of atoms are required to make a compound.
d. mixtures can be made of two elements, two compounds or an element and a compound.

Explanation:

A molecule is formed by two or more atoms bonded together, so option a is true. A compound is made of at least two types of atoms, so option c is true. Mixtures can consist of two elements, two compounds, or an element and a compound, so option d is true. Pure substances include both elements (made of one - type of atom) and compounds (made of more than one - type of atom), so option b is false as it wrongly defines pure substances as being made of only one type of atom.

Answer:

B. Pure substances are made of only one type of atom.