题目

在t ℃时，将a g NH3完全溶于水，得到V mL溶液，假设该溶液的密度为ρ g·mL－1，溶质的质量分数为w，其中含有NH4+的物质的量是b mol，下列叙述正确的是（     ） A．溶质的质量分数w＝×100% B．溶质的物质的量浓度c＝ mol·L－1 C．溶液中c(OH－)＝ mol·L－1＋c(H＋) D．向上述溶液中加入V mL水，所得溶液的质量分数大于0.5w根据汉语提示用单词的正确形式补充句子。小题1:There is no _______________(电) in the wire. Don’t worry. You can touch it.小题2:You should always read the _________________ (说明) carefully before taking medicines.小题3:He tried to get rid of the seaweed __________________(漂浮) on the surface of the water.小题4:During festivals, shops are decorated with ______________________(吸引人的) things so as to attract customers.小题5:I__________________(完全) forget about my appointment with the denist.