Answer:
c. Histidine
Explanation:
Histidine is a compound that is normally used for the generation of protein. Three amino acids commonly have basic side chain when the pH is neutral. The conjugate acid in histidine has a pKa of approximately 6. Based on the description of the experimental analysis provided in the statement, the right option is option c.
Answer: Compound
Explanation:
Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Copper 
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water 

Thus as it give that the red sample on being heated, a gas is released and a blue powder is left after the heating. Thus the given sample is a compound.
The kinetic energy of an object increases when heat is added.
Ranking of the atom from highest to lowest is as follows:
Highest
Arrow = from outer edge to center
2nd Highest
Arrow = second closest ring to the outer edge to center
3rd Highest
Arrow = middle circle to center
Lowest
Arrow = outer edge to middle circle