Pick from: + h2o; + burning coal; + hydrogen; + freezing; + heating homes; + chlorofluorocarbons; + cigarettes; + gasoline;
Q: Fact 1: Carbon monoxide is a gas produced by furnaces and other devices that burn fuel. Fact 2: Gas furnaces heat homes for up to 20 years. Given the two facts above, what produces carbon monoxide?
A:
heating homes