Substances have different tendencies to donate or accept electrons. When a really good donor meets a great acceptor, the chemical reaction releases a lot of energy. Oxygen (O2) is the best electron acceptor and is used in many aerobic reactions (reactions with oxygen). Hydrogen gas (H2) is a good electron donor.
When O2 and H2 are combined, along with a catalyst, water (H2O) is formed. This example of a redox reaction can be written like this:

Answer:
I GOTCHUUU :)
Explanation: warm winters and cool summers
Answer:
O a polymer
Explanation:
When many repeating simple subunits are joined together, this results into a polymer.
The simplest unit or smallest unit of any substance is called a monomer. When many units of a monomer joins together, a polymer results.
- For proteins, the monomeric unit is amino-acid.
- When they combine they form longer chain molecules called proteins.
- For carbohydrates, the monomeric unit is called glucose.
- When they are combined they give us a wide range of carbohydrate molecules.
Heterogenous mixtures are unevenly mixed. Like oil and vinegar in vinaigrette if it is not emulsified well enough and they separate. Any case where two things are not evenly distributed within each other.
Homogenous mixtures are evenly mixed throughout. Like salt water or kool-aid (when it's mixed).
Hope this helps!
I'm not 100% sure but I'm leaning towards D. :)
