Question

what do these two changes have in common? a log decomposing in the woods making paper from wood select all that apply. both conserve mass. both are changes of state. both are caused by cooling. both are only physical changes.

Explanation:

1. Law of Conservation of Mass: According to the law of conservation of mass, mass is conserved in both physical and chemical changes. A log decomposing (a chemical change) and making paper from wood (a physical change) still have the mass of the original wood material accounted for in the products (e.g., decomposed matter like soil - related substances for decomposition, and paper - product for making paper).
2. Elimination of other options:

• Changes of state: Changes of state (e.g., solid - liquid - gas transitions) are not relevant here. Decomposing a log involves biological and chemical reactions (not a simple state change), and making paper from wood is more of a mechanical and physical - process (like pulping, but not a state change).
• Caused by cooling: There is no indication that cooling is the cause for either a log decomposing (which is often due to biological activity and environmental conditions like moisture, not specifically cooling) or making paper from wood (which involves processes like pulping, bleaching etc., not cooling).
• Only physical changes: A log decomposing is a chemical change (new substances like carbon dioxide, water (released as vapour or in soil moisture), and organic - rich soil components are formed). Making paper from wood is a physical change (but since one of the processes is chemical, this option is incorrect).

Answer:

Both conserve mass.