Answer:
A
Explanation:
The first option is the only option where new products are formed.
In the D option no new product is formed.
Same goes with option C.
In B no new products are formed.
Change is said to be taken place only with formation of new products from reactants.
Answer: Option (C) is the correct answer.
Explanation:
When chemical composition of a substance is not changing in a chemical reaction then it is known as a physical change.
For example, when water change state, from ice to steam then it means solid state is changing into gaseous state.
Therefore, it is a physical change.
And, a reaction which causes change in chemical composition is known as a chemical change.
For example, 
Thus, we can conclude that we can see water change state, from ice to steam. This is a physical change in matter.
Answer:
I think the answer is A - they used X-ray analysis.
Explanation:
Answer:
Iron and Oxygen
Explanation:
Fe is Iron and O2 is Oxygen
What are the phrases to choose from?