200 cm3 of air was passed over heated copper in a syringe several times to produce copper (II) oxide.
When cooled, the final volume of air recorded was 158cm3. Estimate the percentage of oxygen in the air?
- 31%
- 27%
-
21%
- 19%
The correct answer is: C
Explanation
Volume of O2 used = 200 - 158 = 42 cm3% of O2 = (42)/(200) x 100% = 21%