中子数比质子数多1个的原子A,其阳离子An+ 核外有X个电子,则A的质量数为
A.2(x+n) B.2(x-n) +1 C.2(x +n) +1 D.n+2
C
解析:阳离子An+ 核外有X个电子,质子数为X+n,N=X+n+1,A=2(x +n) +1