下列对分子、原子、离子的认识，正确的是（ ）
A．分子是保持物质性质的最小粒子
B．原子是最小粒子，不可再分
C．原子得到或失去电子后形成离子
D．分子可以构成物质，原子不能构成物质
答案：C
A、根据分子是保持物质化学性质的最小粒子，故A说法错误；
B、根据原子是化学变化中最小的粒子，不可再分，故B说法错误；
C、根据原子得到或失去电子后形成离子，故C说法正确；
D、分子和原子都是构成物质的基本微粒，错误；
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