Directions: Each set of lettered choices below refers to the numbered questions or statements immediately following it. Select the one lettered choice that best answers each question or best fits each statement. A choice may be used once, more than once, or not at all in each set. The following questions refer to the energy sources listed. (A) Uranium-238 (B) Coal (C) Natural gas (D) Oil (E) Solar Currently proven global reserves are expected to be largely exhausted within the next 50 years.1. Is primarily responsible for acid rain in northeast United States2. Is renewable3. Currently proven global reserves are expected to be largely exhausted with in the next 50 years4. Occurs naturally in bedrock and leads to the formation of radon

Several climate feedback loops to increase temperatures from the last glacial 20,000 years ago to interglacial conditions today. which of the below is a negative feedback loop rather than a positive feedback loop? a. warming temperatures and more rainfall globally at the end of the last glacial period caused increased growth of vegetation which would act to decrease atmospheric carbon dioxide levels. b. warming of the oceans at the end of the last glacial period releases carbon dioxide to the atmosphere (because less carbon dioxide can dissolve in warmer water). c. warming temperatures at the end of the last glacial period resulted in thawing of permafrost over large areas which released carbon dioxide to the atmosphere. d. warming temperatures at the end of the last glacial period caused a reduction in ice covered areas (sea ice, ice sheets and snow) which decreased the earth's albedo.