挑战习题
1/5单选题
难度:

1.如图为空气成分示意图(按体积计算),其中“a”代表的是
A 氧气
B 氮气
C 二氧化碳
D 稀有气体
提示1:
5qC55o2u56m65rCU55qE5oiQ5YiG5Y+K5ZCE5oiQ5YiG55qE5L2T56ev5YiG5pWw6L+b6KGM5YiG5p6Q5Yik5pat5Y2z5Y+v44CC
正确答案:Qg==
56m65rCU55qE5oiQ5YiG5Y+K5ZCE5oiQ5YiG55qE5L2T56ev5YiG5pWw5YiG5Yir5piv77ya5rCu5rCU5Y2gNzgl44CB5rCn5rCU5Y2gMjEl44CB56iA5pyJ5rCU5L2T5Y2gMC45NCXjgIHkuozmsKfljJbnorPljaAwLjAzJeOAgeWFtuWug+awlOS9k+WSjOadgui0qOWNoDAuMDMl77yO55Sx5Zu+5Y+v55+l77yMYeWNoOeahOS9k+enr+WIhuaVsOacgOWkp++8jOaYr+awruawlO+8jjxicj7mlYXpgIlC77yO