Sara is watching television when the power goes out. When she walks to the kitchen to get a candle, she knocks over a chair. She lights a match and holds it to the wick of the candle. She uses the light from the candle to find her way to the chair, which she picks up and sits in. Which of the events was a chemical change? *

She lights a match and holds it to the wick of the candle.

Explanation:

Chemical change produces the required products of reactants by an irreversible reaction. For there to be a chemical change, a chemical reaction between reactants must occur.

Lighting of a match is a chemical change in which the friction between the match box and the gun powder on the stick produces a flame. This reaction produces a product by an irreversible process. After the flame burns out the wick of the candle, it can not be reversed.

the answer is c.) there is a warm front in region a and a stationary front in region b.