Hydrofluorocarbons (HFCs) are organic compounds that contain carbon, fluorine, and hydrogen atoms. They are frequently used in air conditioning and as refrigerants in place of the older chlorofluorocarbons such as freon. Their replacement of freon was phased in as a way to mitigate the environmental damage by persistent chlorofluorocarbons (CFCs). However, HFCs are not without their own environmental consequence. What is the trade off by replacing CFCs with HFCs?

A)CFCs contributed to global warming while HFCs diminish the stratospheric ozone layer.
B)CFCs contribute to lung cancer incidence while HFCs contribute to neurological damage in humans. C)CFCs contribute to ozone layer destruction while HFCs contribute to ground-level photochemical smog. D)CFCs destroyed the stratospheric ozone layer and HFCs are strong greenhouse gases, which contribute to global warming.

Amountain created from tectonic activity would be considered which type of landform ? a) primary landform b) secondary landform

What was the most difficult obstacle to overcome in the creation of an autonomous state after indian independence was achieved? a british willingness to go to war to retain the region b. religious differences between hindus and muslims c. ethnic differences between tribal regions d. indian princes' inability to decide on a format of government

1. in 1492, spain expelled after being under their rule for centuries. a. the portuguese b. the basques c. the castilians d. the moors 2. an important cultural center during the renaissance was the city of a. milan b. bologna c. florence d. naples 3. what is the connection between the minoan civilization and a volcanic eruption on thera? a. the earthquake happened a century before the collapse of the civilization. b. the earthquake created a graben. c. the earthquake caused the collapse of the civilization. d. the earthquake caused a volcanic eruption. 4. throughout history, other cultures influenced greece through a. military conquest b. shared ideals c. trade agreements 5. geographically, spain is isolated from the rest of europe by a. portugal b. the atlantic ocean c. the pyrenees mountains d. narrow coastal plains 6. most of central spain is known as the meseta, which is the spanish word for a. mountains b. plateau c. peninsula d. plains 7. for the people of ancient greece, the  iliad, and the  odyssey  a. copied western ideals b. were not popular c. presented community standards d. were children’s poems\ 8. western cultures got many of their ideas about from ancient greece. a. warfare b. democracy c. education d. agriculture 9. how is greece’s natural vegetation similar to that of other mediterranean countries? a. it has been damaged by forest fires. b. it is mainly deciduous forests. c. it grows rapidly in the wet climate. d. it has been reduced to scrub vegetation by overgrazing. 10. what is the most productive agricultural area in italy? a. the alps b. the po valley c. southern italy d. the apennines 11. many factories in northern italy use for energy. a. coal b. hydroelectricity c. nuclear energy d. natural gas 12. what major landform covers much of italy? a. the apennines b. the po river valley c. the alps