问题 填空题

(8分)水的硬度表示方法是:将水中的Ca2+、Mg2+质量折算成CaO的质量。通常把1L水中含有10mg CaO称为1度,1L水中含有20mg CaO即为2度,以此类推。8度以上为硬水,8度以下为软水。我国规定饮用水的硬度不能超过25度。

(1)日常生活中,可用            检验某水样是硬水还是软水。

(2)Ca(HCO3)2加热时会分解产生一种白色沉淀(水垢的主要成分)和两种常见的氧化物,请写出发生反应的化学方程式                                                 。河水、井水中溶有一定量的Ca(HCO3)2,饮用前可采取          的方法来降低水的硬度。

(3)家用热水瓶一旦产生水垢,其保温性能会降低。用稀盐酸可除去上述水垢,发生反应的化学方程式为                                              

(4)俗话说“水滴石穿”,说的是石灰石的主要成分在雨水和二氧化碳的共同作用下生成了可溶的Ca(HCO3)2,请你写出该反应的化学方程式:                               

答案

(1)肥皂水(1分)(2)2Ca(HCO3)2===CaCO3↓+H2O+CO2↑(2分) 加热煮沸(1分)

(3)CaCO3+2HCl===CaCl2+H2O+CO2↑。(4) CaCO3+H2O+CO2="==" Ca(HCO3)2。(各2分)

(1)用肥皂水可以鉴别硬水和软水,泡沫多的是软水,泡沫少的是硬水;

(2)反应物是碳酸氢钙,生成物是碳酸钙和水、二氧化碳;硬水软化的方法是蒸馏或煮沸;

(3)反应物是碳酸钙和盐酸,生成物是氯化钙、水、二氧化碳,用观察法配平,方程式为CaCO3+2HCl===CaCl2+H2O+CO2↑;

(4)碳酸钙与水、二氧化碳共同作用下可生成可溶性的碳酸氢钙,方程式为CaCO3+H2O+CO2="==" Ca(HCO3)2

完形填空

When older honeybees take on tasks usually handled by younger bees, aging of their brains is effectively changed, a new study finds. The discovery suggests that in humans, social involvement ought to be considered

in addition to drugs as a way to treat age-related dementia(痴呆).

“We knew from previous research that when bees stay in the nest and take care of larvae—the bee babies---they remain mentally able as long as we observe them,” explained Gro Amdam, who led the research at Arizona State University. “However, after a period of nursing, bees fly out gathering food and begin aging very quickly.”

“After just two weeks, foraging(觅食的)bees have worn wings, hairless bodies, and more importantly, lose the brain function—-basically measured as the ability to learn new things,” Amdam said in a statement.

Amdam and his colleagues wanted to find out what would happen if they “asked” the foraging bees to take care of larval babies again. To find out, they removed younger nurse bees from a nest, leaving the older foraging bees to face a choice: forage or care for the larvae. Some of the older returned to searching for food, and others switched to caring for the nest and larvae. After ten days, about fifty percent of the older bees that had chosen to care for the nest and larvae had “greatly improved their ability to learn new things.”

The researchers also discovered changes in the proteins in the brains of the bees whose learning ability had improved. One of the proteins that changed, called Prx6, is also found in humans and is known to help protect against dementia.

“Maybe social involvement is something we can do today to help our brains stay younger,” Amdam says. “Since the proteins being researched in people are the same proteins bees have, these proteins may be able to respond to specific social experiences.”

Other studies have shown several non-drug methods can help improve brainpower in older people, including going for walks and taking music lessons.

The findings, announced this week, are detailed in the journal Experimental Gerontology.

小题1:What does the underlined word “they” in Paragraph 4 refer to? (No more than 5 words)

小题2:When do the brains of older bees age very fast? (No more than 9 words)

小题3:What is Amdam’s suggestion for old people to prevent dementia? (No more than 6 words)

小题4:What is the best title for the text? (No more than 6 words)

单项选择题