Im confused here. Add the rest of the question for me to help you
Answer:
20.0928.
Explanation:
The average atomic mass is (90 * 19.992 + 10* 21) / 100
= 20.0928.
The density of CO2 getting from experiment is 0.1/0.056 = 1.79 g/L. The percent error of this is (1.96 -1.79)/1.96*100%=8.67%. So the approximate percent error is 8.67%.
The drawing is correct because there are 12 atoms of each type on each side of the arrow.