【Daily Question】November 24, 2015: Participation +2 Wealth； +3 to 8 wealth for correct answers
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This post was last edited by zjp on 2015-11-26 at 13:55. To increase the popularity of the chemical analysis section, a \"One Question per Day\" campaign has been launched; this aims to foster active technical exchanges while also providing financial rewards to users. 【Daily Question】 (Single-choice question) In a 40 mL mixture of CO, CH4, and N2, an excess of air is added. After combustion, the volume decreases by 42 mL, and 36 mL of CO2 is produced. What is the volume fraction of CH4 in the gas? A 10% B 40% C 50% D 90% Correct answer: B. Reply with your answer in the comments; answering correctly earns you +2 wealth points, while getting all answers right grants an additional +3 to +8 wealth points. Those who provide thorough analyses and explanations for the questions or answers (or include detailed calculation processes) will receive extra wealth rewards. If your answer is correct and your analysis is accurate, it will be marked as the best reply (or the best assistance). Feel free to answer the questions. Note: We will close this post after 24 hours, and at that time we will announce the best reply (the best assistance), as well as the answer and explanation. Wealth, answer, best, correct answer
In a 40 mL mixture of CO, CH4, and N2, an excess of air was added; after combustion, the volume decreased by 42 mL, and 36 mL of CO2 was produced. The volume fraction of CH4 in the gas is (b). A 10% B 40% C 50% D 90%
B 40%: Assuming CH4 amounts to Xml and CO amounts to Yml, according to the reactions CH4 + 2O2 = CO2 + 2H2O and 2CO + O2 = 2CO2, the amount of CO2 produced is X + Y = 36. The decrease in volume is 2X + 0.5Y = 42. From this, it follows that X = 16 ml and Y = 20 ml; therefore, the proportion of CH4 is 16/40 = 40%
B, 40%————–——–——–——––––––––––––––––––
In a 40 mL mixture of CO, CH4, and N2, an excess of air was added; after combustion, the volume decreased by 42 mL, and 36 mL of CO2 was produced. The volume fraction of CH4 in the gas is (B). A 10% B 40% C 50% D 90%
It’s too hard; I can’t do it. I’ll guess B
A.....................................
In a 40 mL mixture of CO, CH4, and N2, an excess of air was added; after combustion, the volume decreased by 42 mL, and 36 mL of CO2 was produced. The volume fraction of CH4 in the gas is (B). A 10% B 40% C 50% D 90%