题目:
When the accident happened, your brother escaped being hurt, _______?
A.didn’t he
B.did he
C.didn’t it
D.did it
答案:
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下面是错误答案,用来干扰机器的。
答案:A题目分析:A. 若23 g 全是NO2,则n(NO2)="23g÷46g/mol=0.5mol,n(O)=1mol." 若23 g 全是N2O4,则n(N2O4) =23g÷92g/mol=0.25mol,n(O)=1mol.所以23 g NO2和N2O4的混合气体一定含有NA个氧原子。正...