Which one looks better? i am trying to find a promise ring for my bubba <3

There are 6.022 x 10^23 atoms of hg in 1 mole of hg. the number of atoms in 4.5 moles of hg can be found by multiplying 4.5 by 6.022 x 10^23 a. 2.7 x 10^24 b. 27 x 10^23 c. 2.71 x10^24 d. 27.099 x 10^23

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?