Well, it seems like you've stumbled upon a chemistry question. Let's see if I can add a little humor to help explain it to you!
To find the value of Kc for the reaction, we need to use the equilibrium concentrations of the reactants and products. In this case, the only given concentration is [SO2] at equilibrium, which is 3.50x10^-5 Molar.
Now, remember the expression for Kc. It's like a secret code that tells us how much the reaction loves to be balanced. In this case, the code is Kc = [SO3]^2 / ([SO2]^2 x [O2]).
Since there were initially 0.0300 moles of each reactant in a 10.0L flask, we need to convert moles to Molarity. So, to find the equilibrium concentration of [SO3], we divide the moles by the volume of the flask: [SO3] = 0.0300 moles / 10.0 L = 0.0030 Molar.
Now, substitute these values into the expression for Kc: Kc = (0.0030^2) / ((3.50x10^-5)^2 x [O2]).
But wait! We still need to find the concentration of [O2]. Since there is no given information about it, we have to use the stoichiometry of the reaction to figure it out. According to the balanced equation, for every 2 moles of SO2, we need 1 mole of O2.
Since the initial moles of SO2 was 0.0300, we only used half of that, which is 0.0150 moles of O2. Dividing by the volume of the flask, we get [O2] = 0.0150 moles / 10.0 L = 0.0015 Molar.
Now, substitute this final piece of information into the expression for Kc: Kc = (0.0030^2) / ((3.50x10^-5)^2 x 0.0015).
After doing the math, you'll find that Kc is approximately 1.9x10^7. So, the correct answer is option B!
I hope my clowning around with chemistry helped you understand the concept of Kc a little better. Keep up the good work, and remember that humor can always lighten up even the toughest chemical equations!