To determine which molecules are compounds, we need to understand what a compound is. A compound is a substance formed when two or more different elements are chemically bonded together.
Given the molecules:
1. [tex]$NaHCO_3$[/tex] (Sodium bicarbonate)
2. [tex]$O_3$[/tex] (Ozone)
3. [tex]$Cl_2$[/tex] (Chlorine gas)
4. [tex]$C_8H_{18}$[/tex] (Octane)
Let's analyze each molecule:
1. [tex]$NaHCO_3$[/tex] (Sodium bicarbonate): This molecule contains sodium (Na), hydrogen (H), carbon (C), and oxygen (O). Since it is composed of more than one different element, it is a compound.
2. [tex]$O_3$[/tex] (Ozone): This molecule consists only of oxygen atoms. Since it is made up of only one type of element, it is not a compound, but a molecule of an element.
3. [tex]$Cl_2$[/tex] (Chlorine gas): This molecule is composed solely of chlorine atoms. Similar to [tex]$O_3$[/tex], it is not a compound but a molecule of an element.
4. [tex]$C_8H_{18}$[/tex] (Octane): This molecule is composed of carbon (C) and hydrogen (H). Being made up of more than one different element, it is a compound.
Thus, the two molecules that are compounds are [tex]$NaHCO_3$[/tex] and [tex]$C_8H_{18}$[/tex].
Therefore, the correct answers are the first and fourth molecules, which corresponds to:
1. [tex]$NaHCO_3$[/tex]
4. [tex]$C_8H_{18}$[/tex]
