【单选题】______ plants, which manufacture their own food, animals obtain nourishment by acquiring and ingesting their food.
【判断题】用双硫腙光度法测定Pb2+, Pb2+的浓度为0.08mg/50mL,用2cm比色皿在520nm下测得T=53%,经计算,ε=8.9×103L·mol-1·cm-1。
【单选题】Successful education is the acquiring of knowledge from ______.
A.
classrooms, laboratories and museums
C.
intimate association between beginners
【单选题】用双硫腙光度法测定 Pb 2+ (其摩尔质量为 207.2g/mol ),若 50ml 溶液中含有 0.1mg Pb 2+ 。用 1cm 比色皿在 520nm 下测得透光度为 10% ,则此有色物的摩尔吸光系数为:( )。
【判断题】用双硫腙光度法测定Pb 2+ , Pb 2+ 的浓度为0.08mg/50mL,用2cm比色皿在520nm下测得 T =53%,经计算,ε=8.9×10 3 L·mol -1 ·cm -1 。
【单选题】Other businesses, such as insurance companies, are more concerned with acquiring a central position so that they are ______ to the urban population.
【简答题】________ evidence that language-acquiring ability must be stimulated. A) If being B) It is C) There is D) There being
【简答题】用双硫腙光度法测定Pb 2+ ,Pb 2+ 的浓度为0.08mg/50cm 3 ,用2cm比色皿在520nm处测得T=53%。求k=?(Pb原子量207.2。)
【单选题】螺旋传动中的螺母多采用青铜材料,这主要时为了提高_________的能力。
【简答题】用双硫腙光度法测定 Pb 2+ 。 Pb 2+ 的浓度为 0.08mg / 50 mL ,用 2cm 比色皿在 500nm 下测得 T =53 %,求 κ 。