Question

what do these two changes have in common? a log decomposing in the woods salt and vinegar removing tarnish from a penny select all that apply. both are changes of state. both are caused by heating. both are chemical changes. both conserve mass.

Explanation:

1. A log decomposing in the woods involves biological - chemical processes where organic matter is broken down by microorganisms, forming new substances.
2. Salt and vinegar removing tarnish from a penny is a chemical reaction where the acidic vinegar and salt react with the copper - oxide (tarnish) on the penny to form new chemical compounds.
3. Chemical changes involve the formation of new substances, and in both cases new substances are formed.
4. According to the law of conservation of mass, in any chemical or physical change, mass is conserved. So both these chemical changes conserve mass.
5. These are not changes of state (solid - liquid - gas transitions) and not caused by heating specifically.

Answer:

C. Both are chemical changes.
D. Both conserve mass.