题目根据反应R+2O2 点燃 ‾ CO2+2H2OR+2O_{2}\frac{\underline{\;点燃\;}}{\;}CO_{2}+2H_{2}OR+2O2点燃CO2+2H2O,推断RRR的化学式是（ ）A.CH4CH_{4}CH4B.C2H2C_{2}H_{2}C2H2C.C2H4C_{2}H_{4}C2H4D.C2H6OC_{2}H_{6}OC2H6O知识点：质量守恒定律的实验探究章节：科学探究 / 科学探究能力
