During a chemical change, substances react to form a new substance. some signs of chemical change are gas formation, a change in color, or the production of heat. do you think the reaction between calcium carbonate and vinegar is a chemical change? why?

Reaction :-

CaCO3 + CH3COOH → Ca(CH3COO)2 + H2O + CO2

Yes it is a chemical change as we know that chemical changes result in formation of new substances, and in this reaction calcium acetate, carbon dioxide, and water are produced.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

the answer is 1260

you spend 7 hours in school for 1 school day with 5 school days in 1 school week with 36 school weeks in a school year.

7*5*36= 1260 it's all about multiplying