Question

(1999年全國，3)下列說法正確的是?

(A)Ra衰變?yōu)?IMG align="absmiddle" height=25 src="http://thumb.zyjl.cn/pic1/1898/img/02//73//98/189802739810000798/2.gif" width=20 v:shapes="_x0000_i1067">Rn要經(jīng)過1次α衰變和1次β衰變?

(B)U衰變?yōu)?IMG align="absmiddle" height=25 src="http://thumb.zyjl.cn/pic1/1898/img/02//73//98/189802739810000798/4.gif" width=20 v:shapes="_x0000_i1069">Pa要經(jīng)過1次α衰變和1次β衰變?

(C)Th衰變?yōu)?IMG align="absmiddle" height=25 src="http://thumb.zyjl.cn/pic1/1898/img/02//73//98/189802739810000798/6.gif" width=19 v:shapes="_x0000_i1071">Pb要經(jīng)過6次α衰變和4次β衰變?

(D) U衰變?yōu)?IMG align="absmiddle" height=25 src="http://thumb.zyjl.cn/pic1/1898/img/02//73//98/189802739810000798/8.gif" width=20 v:shapes="_x0000_i1073">Rn要經(jīng)過4次α衰變和4次β衰變?

Answer 1

答案：BC