Which polymer is used to stabilize nanoparticles in an aqueous dispersion? a. polystyrene b. polymethacrylic acid c. DNA d. PEG e. polycyanoacrylate

First, let's briefly understand the polymers mentioned in the options. a. Polystyrene - A common plastic used in a variety of applications, including packaging materials and insulation. It is not typically used for stabilizing nanoparticles in aqueous dispersions. b. Polymethacrylic acid - A polymer known for its anionic properties which can be used to stabilize nanoparticles. c. DNA - A molecule responsible for the storage of genetic information. It is not a polymer used for stabilizing nanoparticles in aqueous dispersions. d. PEG (Polyethylene Glycol) - A versatile polymer that has a wide range of applications, including improving solubility and stability of nanoparticles in aqueous dispersions. e. Polycyanoacrylate - An adhesive compound that is not typically used for stabilizing nanoparticles in aqueous dispersions.

Based on the understanding of the polymers in step 1, we can eliminate options a, c, and e, since they are not typically used for stabilizing nanoparticles in aqueous dispersions. Now, we are left with two options: Polymethacrylic acid (option b) and PEG (option d). Both polymers have applications in stabilizing nanoparticles, however, PEG is more commonly used and known for its effectiveness in stabilizing nanoparticles in aqueous dispersions. Therefore, the correct answer is: d. PEG (Polyethylene Glycol)