Choose the correct stability order of the given free radicals.
For the reaction: 2SO2 + O2 → 2SO3, the rate of disappearance of O2 is \( 2 \times 10^{-4} \, \text{mol L}^{-1} \text{s}^{-1} \). What is the rate of appearance of SO3?
A tetrapeptide is made of naturally occurring alanine, serine, glycine, and valine. If the C-terminal amino acid is alanine and the N-terminal amino acid is chiral, the number of possible sequences of the tetrapeptide is: