Mr. greenjeans wants to know which fertilizer grow the biggest pumpkins. he plants three pumpkin seeds of the same variety and then uses three different types of fertilizer on the three seeds. the seeds receive the same amount of fertilizer, water and sunlight. mr. greenjeans monitors the pumpkin seeds' growth for three months.
how could mr. greenjeans improve his experiment?
a) mr. greenjeans needs a control group for comparison.
b) mr. greenjeans should use corn and radish seeds as a comparison.
c) mr. greenjeans should use three different types of pumpkin seeds.
d) mr. greenjeans probably should monitor the pumpkins for a longer period of time.

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.

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."