题干

按如图所示的装置进行实验:A极是铜锌合金,B极是纯铜,电解质溶液中含有足量的铜离子,通电一段时间后,若A极恰好全部溶解,此时B极质量增加7.68g,溶液质量增加0.03g,则A合金中Cu、Zn的物质的量之比为(   )

A:4:1

B:3:1

C:2:1

D:1:1

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答案(点此获取答案解析)

B

同类题5

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

        The relationship between parents and teachers is important in the development of a child. The good communication between them is communication that says, “I care about my child, and I value school. ” The best way a parent can show how much he or she values learning is by sending a prepared child to school everyday.  ____Once a child gets behind in class, catching up can be difficult.

        Parents and teachers are partners in student development. A school community is built on relationships established among children, teachers and children's families.

        Here are tips for creating a positive relationship with your child's teacher.

        Meet with your child's teacher in the fall.____—his or her special needs, outside activities, health, and home study habits.

        Look for the positive.____ Share with your child's teacher something you particularly appreciated regarding the teacher's role in the academic and/or social development of your child.

        Letthe teacher know that you want to support the work that is being done in class.Ask for suggestions for expanding school activities into home activities.

____   You can send a note of  thanks when something special takes place in the classroom and your child is involved.

Bewilling to participate in or set up a conference when you or your child's teacher feels a special meeting is needed, such as...

·____

·Your child seems to be deeply upset about something that happened at school.

A.When a child is absent from school,important lessons may be missed.

B.Phone your child's teacher ifnecessary.

C.The teachers need to feel appreciatedfor the job they do.

D.This is a good time for the teacher tolearn more about your child.

E.Express your appreciation to theteacher.

F.The beginning of every term is veryimportant.

G.There is a dramatic drop in yourchild's grades.