【简答题】For all the dinner table, a glass of milk seems to be a constant , at least it was when I was growing up.It was widely believed that milk was integral in building strong bones and teeth. There’s no do...
【简答题】For all dinner tables, a glass of milk seems to be a must. At least it was when I was growing up. It is widely believed that milk is a must in building strong bones and teeth. There’s no doubt that da...
【判断题】焙烤食品表面颜色反应的形成主要是由于食品化学反应中的酶促褐变引起的。
【单选题】下列浓度为 0.1 mol·L -1 的溶液,可用 0.1 mol·L -1 HCl 标准溶液准确滴定的是
A.
NaAc {已知 pK a (HAc)=4.75 }
D.
苯甲酸钠{已知 pK a ( 苯甲酸 ) = 4.21 }
【多选题】常温下,用 0.1 mol·L —1 HCl溶液滴定10.0 mL浓度为0.1 mol·L —1 Na 2 CO 3 溶液,所得滴定曲线如图所示。下列说法正确的是
A.
当V=0时:c(H + )+c(HCO 3 - )+c(H 2 CO 3 )=c(OH - )
B.
当V=5时:c(CO 3 2— )+c(HCO 3 - )+c(H 2 CO 3 )=2c(Cl - )
C.
当V=10时:c(Na + )>c(HCO 3 - )>c(CO 3 2— )>c(H 2 CO 3 )
D.
当V=a时:c(Na + )>c(Cl - )>c(H + )=c(OH - )
【简答题】What do you think of stress? Is it a good thing or a bad thing? Most of the students think stress can do harm (伤害) 46 them in some ways. There’s a story about a ager in a middle school. He even 47...
【单选题】下列溶液中,浓度为0.1 mol · L -1 的是
【单选题】浓度为0.1 mol·L - 1 下列酸或碱,能直接滴定的是
C.
NaAc (HAc的p K a =4.74)
D.
NH 4 Cl (NH 3 的p K b =4.74)
【判断题】焙烤食品表面颜色反应的形成主要是由于食品化学反应中的 酶促褐变 引起的。
【单选题】焙烤食品表面颜色反应的形成主要是由于食品化学反应中的 _______ 引起的。