Question

Though energy cannot be created or destroyed, it can be transferred and transformed. When energy is not in use, it can be stored. Chemical energy is stored in chemical compounds and released through chemical reactions. Think about the ways you have used stored chemical energy.
Which FOUR are true statements about how chemical energy can be stored and released through chemical reactions?
Responses
A As bike tires roll across the sidewalk, friction is created and they become warmer.As bike tires roll across the sidewalk, friction is created and they become warmer.
B Solar energy from the sun is absorbed by solar panels, which transforms to chemical energy when it is used as electricity.Solar energy from the sun is absorbed by solar panels, which transforms to chemical energy when it is used as electricity.
C As food is digested, molecule bonds are broken, allowing new molecules to form that can be used by our bodies.As food is digested, molecule bonds are broken, allowing new molecules to form that can be used by our bodies.
D Energy stored in organic fuels are used for heat and electricity/Energy stored in organic fuels are used for heat and electricity/
E When batteries are connected to a circuit, a reaction occurs inside the cell producing electrical energy.When batteries are connected to a circuit, a reaction occurs inside the cell producing electrical energy.
F Thermal energy causes energy stored in fireworks to convert to kinetic, light, and sound energy.

Answer 1

Correct answers: C, D, E, F.

Brief reasons:
- C: Digestion is a set of chemical reactions that break bonds in food and form new molecules (and release usable chemical energy).
- D: Organic fuels store chemical energy that is released as heat (and used to generate electricity) when they burn.
- E: Batteries produce electrical energy by internal chemical reactions when the circuit is closed.
- F: Fireworks contain chemical energy; heat/ignition triggers chemical reactions that produce light, sound and kinetic energy.

Why A and B are incorrect:
- A describes mechanical → thermal energy from friction, not release of chemical energy.
- B is wrong as written: solar panels convert sunlight to electrical energy (not directly to chemical energy).