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: helium(He)
Explanation: Helium has only 2 electrons in the outermost energy level, but all of the other elements in its column have eight.
Some physical properties that a pencil would have is, color, density, texture, hardness (in this case the lead is soft). phase (liquid,solid gas), shape, size. physical properties describe the look and feel of a substance. I hope this helps