Answer:
Explanation: A chemical change is a reaction in which chemical composition of the substance changes. Some bonds are broken and some new bonds are formed.
The reactants are written in terms of their chemical formula on the left hand side and the products are written in terms of their chemical formula on right hand side with a arrow in between. The chemical symbols are followed by their physical states such as (l) for liquid, (s) for solid, (g) for gas and (aq) for aqueous.
Thus the only reaction producing a gas is 
People had asked this many times and that is why they came up with methods and standards that will answer these type of questions. You can look it up in the NIST or the National Institute for Standards and Technology.
Answer: There are 78.26 mL of a 0.0023M strontium hydroxide solution are needed to completely react 15.0 mL of 0.012M hydrochloric acid.
Explanation:
Given:
= 0.0023 M,
= ?
= 15.0 mL,
= 0.012 M
Formula used to calculate volume of strontium hydroxide solution is as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that there are 78.26 mL of a 0.0023M strontium hydroxide solution are needed to completely react 15.0 mL of 0.012M hydrochloric acid.
Answer:
2NaCl + FeO —-> 2Na2O + FeCl2
Explanation: