题目

—I offered two yuan to________for your seat.Would you take it? —All right. A．change                                               B．exchange C．give                                                   D．sit 答案：exchange交换。exchange for sth.为了某物而交换。 答案： B设NA表示阿伏加德罗常数的值，下列说法中正确的是 [     ]A．1 mol Na+ 所含质子数为10NA B．1克氢气所含分子数约为6.02×1023 C．22.4 L SO2所含的分子数为NA D．2.3克金属钠变为钠离子时失去的电子数是0.1NA