(2) Copper does not react with carbon monoxide at high temperature, so the powder does not change color and the clarified limewater will not be turbid; Iron oxide can react with carbon monoxide at high temperature to produce black iron powder and carbon dioxide. After full reaction, the powder turns black and limewater is clarified.

The possible phenomena in the experimental conclusion are that red powder does not change color and limewater does not change turbidity. Suppose 1 holds? All the red powder turns black, and the lime water becomes turbid? Hypothesis 2 holds? Part of the red powder turns black and the lime water becomes turbid? Suppose 3 holds (4)① Carbon monoxide reduces iron oxide to produce iron and carbon dioxide, and the equation is 3CO+Fe2O3? High temperature? . ? 2Fe+3co 2；

② Carbon dioxide reacts with limewater to generate calcium carbonate precipitate and water, and the equation is: Ca (OH) 2+CO2 ═ CaCO3 ↓+H2O;

(3) Carbon monoxide gas is toxic, and direct discharge into the air will cause air pollution, so the tail gas can be burned or collected, lit with alcohol lamp at point B, or collected with plastic bags (balloons);

So the answer is:

(1) mixture of copper powder and iron oxide powder;

(2)

The phenomenon that may occur in the experimental conclusion is that the red powder does not change color, assuming that 1 is true when the clarified limewater remains turbid, all the red powder turns black when the clarified limewater becomes turbid, assuming that 2 is true when the red powder turns black, and 3 is true when the clarified limewater becomes turbid (4)①3CO+Fe2O3? High temperature? . ? 2Fe+3co 2；

②ca(oh)2+co2═caco3↓+h2o； ?

③ Light it with alcohol lamp at point B, or collect the tail gas with plastic bag (balloon).