What is the difference between the coarse adjustment knob and the fine adjustment knob?

COARSE ADJUSTMENT KNOB — A rapid control which allows for quick focusing by moving the objective lens or stage up and down. ... FINE ADJUSTMENT KNOB — A slow but precise control used to fine focus the image when viewing at the higher magnifications. 6.

Coarse adjustment, using the coarse adjustment knobs, raises and lowers the stage more rapidly. Fine adjustment knobs are the smaller knobs and are also used to raise and lower the stage but more slowly and in a more controlled manner under higher magnifications.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

distance, luminosity, brightness, radius, chemical composition, and temperature