题目内容
A.13 B.14 C.15 D.16
D
A.13 B.14
C.15 D.16
A.13 B.14? C.15 D.16?
X元素能形成H2X和XO2两种化合物,该元素的原子序数是( )?
A.13 B.14?
C.15 D.16?