A:用10mL量筒量取7.13mL稀盐酸;
B:用托盘天平称量25.20g NaCl;
C:用广泛pH试纸测得某溶液的pH为2.3;
D:用25mL滴定管做中和滴定时,用去某浓度的碱溶液21.70mL;
某研究小组为探究负氧离子对空气质量有何影响,进行了以下实验:
①在甲、乙两个相同的房间内,通过释放烟雾制造空气污染物浓度较高的环境
②在甲房间内释放一定量的负氧离子,乙房间不做处理
③每隔1小时对甲、乙房间内空气污染物中的PM2.5浓度进行检测,获得的数据经处理后如图所示,请分析回答
China is seeing ______ growing trend in the number of people owning pets and ______ recent survey finds that one in 13 Chinese now keep animals.
有四包真空小包装火腿,每包以标准克数(450克)为基准,超过的克数记作正数,不足的克数记作负数,以下数据是记录结果,其中表示实际克数最接近标准克数的是( )
He entered Beijing University ________. The people in his village are ________ him.