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【简答题】
已知分析天平能称准至土0.1 mg,要使试样的称量误差不大于0.1%,则至少要称取试样多少克? 2、某试样经分析测得所含锰的质量分数(%)为:41.24,41.27,41.23,41.26。求分析结果的平均偏差、标准偏差和变异系数。 3、某矿石中钨的质量分数(%)测定结果为:20.39,20.41,20.43。计算标准偏差s及置信度为95%时的置信区间。
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【简答题】social faux pas
【简答题】用 测定试样中的铁,在波长480nm处用1cm吸收池测定1.2mg 标 准溶液的吸光度为0.120;在同样条件下测定试样溶液,吸光度为0.520,求试液中 的 浓度(mg )
【简答题】social Faux Pas
【简答题】某样品中铁含量约为11mg/L，用分光光度法测定，若取适量样品溶液转移至100mL容量瓶中，加水稀释至刻度，在波长480nm处用2cm比色皿测量，希望此时测量误差最小，应取多少试样?已知ε=1.1×10 4 L/(mol·cm)，M Fe =55.86，测量误差最小时的A值为0.434。
【单选题】By saying "This includes love" (para.2) the author regards love as ____.
A.
that can be achieved through the works of hand
B.
a form of concern for human feeling and spirituality
C.
the most important component of the spiritual world
D.
one of the most sublime and meaningful creative motives
【简答题】“Love your neighbor as yourself' is a saying familiar to most of us. It means that you must have he ability to love and accept yourself in order to form and keep satisfying relationship with others se...
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