题干
Can I help you?
A：Three bananas, please.
B：Three peaches, please.
C：Three oranges, please.
答案(点此获取答案解析）
A
Can I help you?
A：Three bananas, please.
B：Three peaches, please.
C：Three oranges, please.
10.6 g Na2CO3溶于水配制成500 mL 溶液，从中取出20 mL，该溶液中Na＋的物质的量浓度为