Two workers used a force of 100 N to move a sofa 4 meters in 2 seconds how much power

200 watts

Explanation:

First we have to find total work:

W =F(d)

W = 400J

Then plug that answer into the Power formula.

P = W/(t_f-t-i)

P = 400/2s

P = 200 W

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.