I actually had a similar question on my test and this is the answer:
The reason the magnet loses its magnetic properties is is because when you drop the magnet or bump it against something, the domain can get bumped or dropped out of alignment.
Hoped this helped :)
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A dependent variable is how they are recording, measuring or keeping track of the science experiment their doing.
A independent variable is the things/types there using to compare what is the most/least affective in the experiment.
A controlled variable is something that stays the same in the experiment or a group/set used for comparison
Nitrogen and hydrogen
N2 +3 H2 ---> 2NH3
hope that answers the question:)