9) Match the equations with the types of reaction. 2Mg + O2 + 2MgO
2H2O + 2H+ 02
2AgNO3 + Cu + Cu(NO3)2 + 2Ag
C3H3 + 502 + 3C02 + 4H2O

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.

d.) circle motion requires a force to give it a centripetal acceleration.

the answers would be

the first one and the second one