【单选题】把0.1mol·L -1 HAc溶液20mL和0.1mol·L -1 KAc溶液20mL混合得缓冲溶液,该溶液的pH为( )。(HAc的K a =1.76×10 -5 )
【简答题】咨询单位的市场部分析市场,请问市场细分的步骤?
【单选题】分别计算 c (HAc) =0.083mol/L 的 HA c 溶液的 pH 。( pK a(HAc) =4.76 )
A.
c(HAc) =0.083mol/L 的HA c 溶液的 pH 为1.46。
B.
c(HAc) =0.083mol/L 的HA c 溶液的 pH 为2.92。
【单选题】听力原文: Good morning, everybody. Now I'm going to tell you how to buy a ticket for the BART system. Each person must have a ticket. Children aged not more than four do not need a ticket. Since each of y...
A.
A group of 4 children.
B.
Children not more than 4 years old.
C.
Those who ride every day.
D.
Those who are free from work.