Question

what do these two changes have in common?
a log decomposing in the woods
cellular respiration
select all that apply.
both conserve mass.
both are changes of state.
both are caused by cooling.
both are chemical changes.

Explanation:

1. Both conserve mass: All chemical and biological processes follow the law of conservation of mass, where matter is neither created nor destroyed, only rearranged. Both log decomposition and cellular respiration follow this.
2. Both are chemical changes: Log decomposition breaks down the wood's complex organic molecules into new substances via microbial action; cellular respiration breaks down glucose into carbon dioxide and water, creating new chemical compounds. Both involve irreversible chemical transformations.
3. Eliminated options: Changes of state are physical (solid/liquid/gas shifts, no new substances) which does not apply here. Neither process is caused by cooling—decomposition and respiration generate heat, and cooling would slow them.

Answer:

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