Answer:
understanding people, organize notes correctly, learn how to organize your time wisely.
Explanation:
Explanation:
Pure subsance is a substance that is made up of only one type of particle - each piece is the same throughout.
Being present before the reaction but not after means it's no the same (it couldve evaporated)
Answer:
Explanation:
Our 
sample yielded 1g of 
and 16g of 
, but our unknown sample yielded 2 times as much for the same amount of .
What does this mean? that the H:O proportion for the unknown sample is twice the H:O proportion for the sample.
What is the H:O proportion for the sample? As we can see from its formula, it's 1:1, therefore the proportion for the unknown formula must be 2:1.
That means, two H atoms for every O atom. We could write that as: 
and you should recognize that formula, for it is one of the most common compounds on earth, Water.
Hope this helps! If you dont understand balancing equations in general, say so in the comments, I’m happy to help
