【单选题】【消耗次数：1】
分子中存在着带正电荷的原子核和带负电荷的电子，整个分子呈现( ) 。
①
电性不一定
②
不带电
③
正电荷
④
负电荷
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相关题目
【多选题】
下列哪种蛋白质在pH值等于5.0的溶液中带正电荷
①
pI为4.5的蛋白质
②
pI为4.7的蛋白质
③
pI为7.0的蛋白质
④
pI为6.5的蛋白质E
⑤
pI为3.5的蛋白质
【单选题】
关于高斯定理，下列说法中正确的是（） （1）高斯面上的电场强度只与面内的电荷有关，与面外的电荷无关； （2）高斯面上的电场强度与面内和面外的电荷都有关系； （3）通过高斯面的电通量只与面内的电荷有关，与面外的电荷无关； （4）若正电荷在高斯面之内，则通过高斯面的电通量为正；若正电荷在高斯面之外，则通过高斯面的电通量为负。
①
（1）和（4）正确
②
（2）和（3）正确
③
（1）和（3）正确
④
（2）和（4）正确
【单选题】
俗话说“卤水点豆腐，一物降一物”，这其实说的就是胶体的聚沉。向胶体中加入酸、碱、盐，能使胶粒所带电荷被中和，从而“聚集长大”直至生成沉淀。实验证明，凝聚主要取决于胶粒带相反电荷的离子所带的电荷数，电荷数越大，凝聚能力越大，则向Fe(OH)3胶体中加入下列电解质时，其“聚沉值”最小的为(注：Fe(OH)3胶粒带正电荷）
①
NaOH
②
AgNO3
③
BaCl2
④
Na3PO4
随机题目
【单选题】
We are going to have a singing party tonight. Would you like to join us?___________
①
I’m afraid not, because I have to go to an important meeting.
②
Of course not. I have no idea.
③
No, I can’t.
④
That’s all set.
【单选题】
Use daily writing to ______ your communication skills.
①
track
②
discharge
③
contract
④
enhance
【单选题】
The dean of the Philosophy Department requested that the visiting scholar ______ a lecture on the philosopher Sartre.
①
gave
②
give
③
would give
④
had given
【单选题】
It became harder for women married to diplomats(外交家) to _______ their own interests.
①
pursue
②
replace
③
absorb
④
convince
【单选题】
As a result of his hard work, he has gained ______ to the Beijing University.
①
access
②
commitment
③
opportunity
④
reward
【单选题】
Planning so far ahead _____ no sense -- so many things will have changed by next year.
①
made
②
is making
③
makes
④
has made
【单选题】
How can you keep the machine （）when you are away?
①
run
②
to run
③
running
④
being run
【单选题】
I hate people who ____ the end of a film that you haven’t seen before.
①
reveal
②
rewrite
③
revise
④
reverse
【单选题】
Since the matter was extremely _____, we dealt with it immediately.
①
tough
②
tense
③
urgent
④
instant
【单选题】
As to who is to be hired, it is the Human Resources Department（）has the final say.
①
whose
②
those
③
these
④
that