为了区别O2与CO2两瓶无色气体，下列方法中可行的是 （ ）
A．分别观察气体的颜色
B．用燃着的木条分别伸入瓶中
C．分别通入紫色石蕊溶液中
D．用软塑料可乐瓶分别盛满上述两种气体，各倒入1/5容积的水，盖紧瓶盖，振荡
BCD
题目分析：A O2与CO2都无色无味的气体，所以分别观察气体的颜色不区别氧气和二氧化碳，故A不符合题意；B 用燃着的木条分别伸入瓶中，燃烧更旺的是氧气，熄灭的是二氧化碳，故B正确；C 分别通入紫色石蕊溶液中，变红色的是二氧化碳，不变色的是氧气，故C正确；D．用软塑料可乐瓶分别盛满上述两种气体，各倒入1/5容积的水，盖紧瓶盖，振荡，软塑料可乐瓶变瘪的二氧化碳，变化不明显的是氧气，故D正确。故选BCD。
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