1. What is the difference between a homogeneous and a heterogeneous mixture? Give an example of each. Answer: A homogeneous mixture is one that has a uniform composition throughout, such as air or salt water. A heterogeneous mixture is one that has different compositions in different regions, such as oil and water or sand and sugar. 2. What is the difference between an empirical and a molecular formula? Give an example of each. Answer: An empirical formula is the simplest ratio of the elements in a compound, such as CH for benzene. A molecular formula is the actual number of atoms of each element in a molecule of a compound, such as C6H6 for benzene. 3. What is the difference between a strong and a weak acid? Give an example of each. Answer: A strong acid is one that completely dissociates in water, releasing all its hydrogen ions, such as HCl or H2SO4. A weak acid is one that partially dissociates in water, releasing only some of its hydrogen ions, such as CH3COOH or H3PO4. 4. What is the difference between an endothermic and an exothermic reaction? Give an example of each. Answer: An endothermic reaction is one that absorbs heat from the surroundings, such as melting ice or photosynthesis. An exothermic reaction is one that releases heat to the surroundings, such as burning wood or respiration. 5. What is the difference between oxidation and reduction? Give an example of each. Answer: Oxidation is the loss of electrons or increase in oxidation number of an atom or ion, such as Mg -> Mg2+ + 2e-. Reduction is the gain of electrons or decrease in oxidation number of an atom or ion, such as Cu2+ + 2e- -> Cu.