Mechanical advantage may be calculated using all of the following except

a. counting the number of supporting ropes of a pulley system

b. dividing resistance force by effort force

c. multiplying resistance force by effort force

d. dividing effort distance by resistance distance

i dont know

explanation:

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.