When you heat a test tube, what should you do? (select all that apply.)
a. put a stopper in the top of the tube to prevent fumes from escaping.
b. point the tube opening away from your face or the faces of others.
c. look inside the tube often to observe results.
d. pick the tube up with a test tube holder or protected hands.

i think that is new experiments yield untrustworthy data and should be carefully considered, because you don't know what will happen with the experiments.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.

they check for mistakes and stuff