I. Upgrading insulation in homes Use the following information to answer the next question Actions That Can Affect Energy Use in Canada II. Converting vehicles to run on biofuels III. Obtaining fossil fuels from oil sands deposits IV. Providing rebates to consumers to lower the cost of gasoline V. Modifying cars so that less gasoline will be required per kilometre 21. Two actions listed above that increase efficient energy use and therefore promote sustainable development are A. II and III B. III and IV C. I and V D. I and II __ 22. One difference between nuclear reactions and chemical reactions is that in nuclear reactions, A. there is a mass difference between reactants and products B. mass is neither created nor destroyed C. energy is neither created nor destroyed D. the mass of the reactants is double that of the products

21. **C. I and V**<br /><br />Upgrading insulation (I) reduces energy loss for heating and cooling, thus increasing efficient energy use. Modifying cars to use less gasoline per kilometer (V) directly increases fuel efficiency. Both of these contribute to sustainable development by reducing resource consumption.<br /><br />Converting vehicles to biofuels (II) *could* be considered more sustainable than fossil fuels, but it doesn't necessarily increase *efficiency* of energy use. Obtaining fossil fuels from oil sands (III) is resource-intensive and environmentally damaging. Providing rebates (IV) might encourage consumption, counteracting sustainability goals.<br /><br />22. **A. there is a mass difference between reactants and products**<br /><br />Nuclear reactions involve changes in the nucleus of atoms, leading to a small but measurable difference in mass between reactants and products. This mass difference is converted into energy according to Einstein's famous equation, E=mc².<br /><br />While mass-energy is conserved overall (meaning the total mass-energy remains constant), there *is* a detectable change in mass. In chemical reactions, the mass difference is so negligible that it's considered constant for practical purposes. Both chemical and nuclear reactions adhere to the principle of conservation of mass-energy (options B and C), but option A specifically highlights a key distinction between the two types of reactions. Option D is incorrect; there's no fixed ratio of reactant to product mass in nuclear reactions.<br />