某元素的一种同位素X原子的质量数为A，含N个中子，它与H原子组成HmX分子，在ag HmX分子中含质子的物质的量是 ( )
A． (A-N+m) mol |
B． (A-N) mol |
C．( A-N) mol |
D．(A-N+m) mol |
相关试题
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