What volume of gas can be obtained by reacting carbon monoxide (IV) with 40 grams of coke containing 5% impurities?

Given:
m mixture (C) = 40 g
w approx (C) = 5%
To find:
V (CO)
Decision:
CO2 + C = 2CO
w is clean. islands (C) = 100% -5% = 95% = 0.95
m clean in islands (C) = w * m mixture = 0.95 * 40 g = 38 g
n (C) = m / M = 38 g / 12 g / mol = 3.16 mol
n (C): n (CO) = 1: 2
n (CO) = 3.16 mol * 2 = 6.32 mol
V (CO) = n * Vm = 6.32 mol * 22.4 L / mol = 141.6 L
Answer: 141.6 L