Remember significant figures are all non-zero numbers.
Answer:
the empirical formula
Explanation:
I remember learning this last year.
I think it's A, I hope this helps
Here are the solutions
1. Double replacement
2. Combustion
3. Single replacement
4. Synthesis
5. Decomposition.
Single displacement.
Because one element displaced anoother element.
Example:
Fe + Cu SO4 ---> Fe SO4 + Cu .... Fe displaced (and replaced) Cu from Cu SO4