【单选题】If solutions of calcium iodide and ammonium chloride are mixed together in a metathesis reaction, what is the empirical formula for the precipitate which forms ?
E.
A mixture of NH 4 Cl and CaCl 2 forms
【简答题】What volume of 0.1mol/L hydrochloric acid solution should be added to 50 mLof the following solutions respectively to prepare solution at pH =7.00? (1) 0.1mol/L NaOH solution. (2) 0.1 mol/L NH3 soluti...
【简答题】计算下列波形的幅度和频率 ( 经探头接入 ) : ( 1 ) V / div 位于 0.2 档, t / div 位于 2 μ s 档。 1 H = 2div , D = 3div 2 H = 5div , D = 2div . 3 H = 3div , D = 5div ( 2 ) V / div 位于 0.05 档, t / div 位于 50 μ s 档。 1 H = 5div , D = ...
【单选题】Which of the following solutions has the highest pH?
【简答题】计算下列波形的幅度和频率 ( 经探头接入 ) : ( 1 ) V / div 位于 0.2 档, t / div 位于 2 μ s 档。 1 H = 2div , D = 3div 2 H = 5div , D = 2div . 3 H = 3div , D = 5div
【单选题】The lower the spreading factor, the more payload data a signal can convey on the radio interface.
【单选题】The solutions of NH 4 Ac is
【单选题】按CIF TIANJIN成交的合同,卖方完成交货任务是在( )。
【单选题】She has been in Tianjin for ten years. Tianjin has become her second _________.
【单选题】If the following solutions are at the same concentration of 0.1 mol · L -1 , which is the correct ordering of their pH value? ( Ka( HAC )=1.75 × 10 -5 , Ka( HF )=6.8 × 10 -4 , Ka( HCN )=6.2 × 10 -10 )
A.
NaCN >NaAc>NaF>NaCl>NH 4 Cl
B.
NaF>NaAc>NaCN> NaCl>NH 4 Cl
C.
NaAc>NaCN>NaF>NaCl>NH 4 Cl
D.
NH 4 Cl>NaCl>NaF>NaAc>NaCN