First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst.
Answer:
Habitat/Environment. Either can be right
It’s 5211 bc a is 5, B is 2 and D is 1! hope this helps!
The correct answer is A. Recording the sounds of a test tube breaking
Don not know sorryyyyyyyyyuyyyyyyy
