We determined the bottom piece of tape was: a. negative, because it ripped the extra particles off the top piece of tape b. positive, because it was attracted to the plastic rod, which was defined as having negative charge. c. negative, because it was repelled by the other top tape. d. positive, because it was attracted to the bottom tape.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

warm front forms when a moist, warm air mass slides up and over a cold air mass. as the warm air mass rises, it condenses into a broad area of clouds. a warm front brings gentle rain or light snow, followed by warmer, milder weather.

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