为了测定某种石灰石中碳酸钙的质量分数,取5g石灰石样品放入烧杯中,将60g稀盐酸

题型:计算题

问题:

为了测定某种石灰石中碳酸钙的质量分数,取5g石灰石样品放入烧杯中,将60g稀盐酸分成四次加入烧杯中,充分反应后,测得实验数据如下表(样品中的杂质不与盐酸反应也不溶于水):

请你分析并进行有关计算:

(1)哪几次反应后,盐酸有剩余_____________。

(2)石灰石样品中碳酸钙的质量分数。

(3)上述实验结束后,向烧杯内的物质中加入石灰石至不再产生气泡,过滤。求滤液中溶质的质量分数。(结果精确到0.1%)

考点:化学反应方程式的计算关于溶液的计算
题型:计算题

关于产后的护理,下列不正确的是

A.产后30天左右携孩子一起去分娩医院复查
B.检查生殖器官恢复情况以指导计划生育及性生活
C.检查 * * 有无炎症、乳汁的质量及喂养情况
D.检查新生儿生长发育情况
E.检查有无其他内外科疾病以及时就诊

题型:计算题

Kelly Christopher, a student at Lutheran High School in California, US, loves oranges. One day last week, she used a pole(竿子) to pick oranges off trees and collect them in baskets. It's the first time in her 15 years she's picked fruit from trees.

"This is quite different from buying oranges in the supermarket," said Christopher. "Every time I eat an orange, I'll remember this experience."

Christopher was one of the 30 student volunteers at Soil Born Farms. She volunteered as part of a project which was set up in 2009 to help homeowners in South Land Park pick oranges and other fruits out of their backyards. Before, the fruit would rot on the ground or get eaten by animals. Now the fruit is donated to those who need it.

"It is good for many people", said Randy Stannard, who works for the project. "The homeowner gets fruit picked and more people can have healthy food."

"Two harvests (收成 ) were organized in 2009 and volunteers picked 3,000 pounds (1,360kg) of fruit", Stannard said. In 2010, the number was 20,000. This year, Soil Born Farms hopes to get 40,000 pounds. They will harvest every weekend from January to April.

Shannon Galloway, Christopher's science teacher, brought her students into the project this year.

"You're making use of a resource that might be wasted," she said. "I think it's meaningful to everyone."

Donato Frazier, 15, always climbs up a ladder(梯子) and gets on the top of the tree.

"Standing on the treetop is pretty cool," Frazier said. "I can see clearly that many baskets are filled up, and even see that many people are eating healthy fruit because of our volunteer work."                                          

小题1:Christopher and other students went to pick fruits from real trees because they wanted to _____.

A.have some fresh fruit for themselves

B.make some money by selling fruit

C.provide people with more healthy fruit

D.buy some cheap fruit from their neighbors小题2:When was the project set up?

A.In 2008.

B.In 2009.

C.In 2010.

D.In 2011.小题3:What will happen to the fruit if they don’t help the homeowners pick it?

A.The fruit will rot or be eaten by small animals.

B.People who need the fruit will come to pick it.

C.The fruit will be used as a resource for research.

D.Homeowners will pick the fruit and sell it.小题4:What does the underlined word resource mean?

A.资源

B.调查

C.对策

D.娱乐小题5:How do the students feel about their work?

A.It’s interesting and easy.

B.It’s meaningless and hard.

C.It’s meaningful and exciting.

D.It’s tiring and boring.

题型:计算题

小明有4.2元钱,给小华0.5元钱后还比小华多0.3元,小华原有(  )元钱.

A.3.4

B.4.4

C.2.9

D.4.0

题型:计算题

刚性基础施工是指用()等材料建造的基础。

A、砖

B、石

C、混凝土

D、灰土和三合土

题型:计算题

雷电的主要危害是什么?

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