A student performs an experiment to see how catalysts affect the rate of a reaction. He notices that when the reaction is nearly finished, it stops bubbling. He wants to know how much faster the reaction occurs when a catalyst is used. Which is the best method for him to measure his data? Use a stopwatch to record the time it takes for the bubbling to stop. Estimate the time of the reaction by counting aloud. Count the number of bubbles formed by the reaction. Measure the size of the bubbles produced with a ruler.

Which of the following harmful chemicals are found in tobacco smoke? a. carbon monoxide b. carbon dioxide c. nicotine b. carbon dioxide d. both a and c

For which pair of objects would adding the same a

This is important 1. what happens to the speed of molecules in water vapor when it condenses to form a liquid? (2 points) the molecules slow down. the molecules speed up. the molecules slow down and then speed up. the molecules speed up and then slow down. 2. how might human activities change to compensate for a decrease in water supplies? (2 points) humans might build a factory. humans might build drainage systems. humans might extract more water from the ground. human behavior does not change because of the water cycle. i'll be grateful if anyone can answer these 2 questions !