Some of the new cars being made can run on a renewable fuel that is made mostly from corn. Scientists are developing even more renewable fuels to replace gasoline. Why are renewable fuels most likely becoming more important? OPTIONS:
- Renewable fuels release less energy.
- Car fuel tanks are being made smaller.
- The demand for gasoline is decreasing.
- Nonrenewable fuel supplies are limited.
A: Nonrenewable fuel supplies are limited.

Examine each of these chemical equations to determine which equation is correctly balanced. OPTIONS:
- Mg(NO_{3})_{2} + K_{2}CO_{3} -> MgCO_{3} + KNO_{3}
- Mg(NO_{3})_{2} + K_{2}CO_{3} -> MgCO_{3} + 2KNO_{3}
- 2Mg(NO_{3})_{2} + K_{2}CO_{3} -> 2MgCO_{3} + KNO_{3}
- Mg(NO_{3})_{2} + 2K_{2}CO_{3} -> MgCO_{3} + 2KNO_{3}
A: Mg(NO_{3})_{2} + K_{2}CO_{3} -> MgCO_{3} + 2KNO_{3}

During which phase change is heat energy absorbed by a substance? OPTIONS:
- liquid to gas
- gas to solid
- liquid to solid
- gas to liquid
A: liquid to gas

Which of these indicates a physical change that occurs during the process of digestion? OPTIONS:
- the addition of acids to create a ball of food
- the secretion of pepsin to change proteins to peptides
- the breakdown of food substances by digestive juices
- the squeezing of food through the intestines
A:
the squeezing of food through the intestines