Equilibrium is defined as a state of balance or a stable situation where opposing forces cancel each other out and where no changes are occurring. An example of equilibrium is in economics when supply and demand are equal. An example of equilibrium is when you are calm and steady.
Equilibrium is a state of balance in which opposing forces cancel out. In a chemical reaction, the products and reactants are balanced with no tendency to change with time. Thus, there are no observable changes in properties.
A molecule is a group of bonded atoms. Answer a, b, and c all have molecules. For example H2O has the molecule H2 in it. The only compound that doesn't share this trait is answer d: NaCl.
