问题 推断题

(7分)现有A、B、C三种初中常见物质,其中两种为氧化物。请根据下列叙述回答问题。

(1)向A中加入C 物质,则生成B,B为一种碱,A、B含有相同的金属元素,则C为____________。将A放入饱和的B溶液中,出现白色浑浊,该白色浑浊物为_________,发生反应的化学方程式为_______________________。

(2)若A含两种元素,A发生复分解反应同时生成B和C,则A的化学式为_______,该反应的化学方程式为____________________________________________。

(3)若A是一种红色固体,能溶于稀盐酸,得到黄色溶液。且A、B、C三种物质存在下列相互关系A→B→C,则C所属的物质类别可能是______________。

A.酸      B.碱   C.盐    D.氧化物   E.单质

答案

(1)H2O或水       CaO + H2O ="=" Ca(OH)2      Ca(OH)2

(2)HCl      CaCO3 + 2HCl ="===" CaCl+ H2O + CO2↑(其他合理答案给分)

(3)A B C D E   (此空为2分,答对3个以下0分,答对3——4个得1分)

题目分析:(1)根据题意,A、B、C三种物质为初中常见物质,其中两种为氧化物,由于B为一种碱,则说明A、C属于氧化物;根据A、B含有相同的金属元素,说明A是金属氧化物,金属氧化物与水反应生成碱,故C为水,A是氧化钙,B是氢氧化钙;A放入饱和的B溶液中,出现白色浑浊,原因是氧化钙与水反应生成氢氧化钙,同时发出大量的热,使饱和溶液中的水减少,且氢氧化钙的溶解度也变小(氢氧化钙的溶解度随温度的升高而变小),则有溶质氢氧化钙析出。

(2)根据题意,A、B、C三种物质为初中常见物质,其中两种为氧化物,且A含两种元素,若A是氧化物,由于A发生复分解反应同时生成B和C,结合金属氧化物与酸反应生成盐和水可知,A是金属氧化物,如氧化钙,而氧化钙与盐酸反应生成氯化钙和水,符合题意;

若A不是氧化物,则B和C就是氧化物,根据A发生复分解反应同时生成B和C,则B和C应为二氧化碳和水,故A应为盐酸,盐酸和碳酸盐反应生成盐、二氧化碳和水。

(3)根据题意,A是一种红色固体,能溶于稀盐酸,得到黄色溶液,由于黄色溶液是铁离子溶液,所以A是氧化铁。氧化铁可以与酸反应生成铁盐和水,如果B是铁盐溶液,C可以是碱,但不符合A、B、C中有两种为氧化物;如果B是水, C也可以是碱(氧化钙与水反应生成氢氧化钙),C也可以是酸(二氧化碳与水反应能生成碳酸),C还可以是单质(水电解生成氢气和氧气)。

氧化铁还可以与一氧化碳等还原性物质反应,生成铁和二氧化碳等,如果B是铁,可以与氧气反应生成四氧化三铁,故C可以是氧化物;铁也可以与酸或盐反应,生成亚铁盐和单质(氢气或金属),但不符合A、B、C中有两种为氧化物;如果B是二氧化碳,可以与碱反应生成盐和水,故C可以是盐。故选ABCDE。

点评:在解此类题时,首先要将题中有特征的物质推出,然后再推导其他的物质,对于现象不明显的,要根据学过的知识先进行有针对性的猜想,然后再进行验证。

阅读理解

AIDS’ Threat to Asia Grows

NEW DELHI----Just a few years ago, Mala was a typical middle-class Indian housewife. She cooked, cleaned and looked after her two small children.

Last year, her life took a tragic turn. Her husband died of AIDS; she was found out HIV-positive and her mother-in-law took her children away from her, saying they would get the disease. “When friends dropped for a visit, she would introduce me, saying, ‘She is my son’s widow. She has AIDS,’” said Mala. AIDS is now described as “explosive(炸药)” around the world. A study of a hospital in the port city of Durban in South Africa, where the world’s biggest and Africa’s second AIDS conference opened last Sunday, found that almost half the beds in medical wards (病房) were occupied by AIDS patients.

South Africa has one of the world’s fastest growing HIV infections, with 1,700 people infected daily, adding to the 4.3 million, or 10 percent of its population, living with HIV. Until now, Asia has been more successful in holding the AIDS virus than Africa, where the disease has killed about 12 million people.

AIDS is now threatening to surround many of Asia’s poverty-stricken countries. Countries in Asia, such as Cambodia, and Thailand, have HIV infection speeds over 1 percent. But the low speeds hide huge numbers of infected people, because of the population base.

In India, for example, 3.7 million are infected, more than in any other country except South Africa. In China, an estimated 860,000 people (the actual number may be a little larger), mainly drug users, live with HIV/AIDS. Gordon Alexander, a senior advisor for UN AIDS in India, estimates that the number hit by AIDS in Asia will climb about eight million over the next five years from about six million.

In many Asian countries, the battle against HIV is a social and cultural one against public discussion of sexual health put a nationwide media campaign into action to limit the speed of HIV through unsafe sex. Brenton Wong, an official for Singapore’s Action for AIDS, says the actual HIV incidence in the city state of 3.9 million people is at least eight times higher than official data. “Shame and deny is still very, very common so people are afraid to get tested and many times won’t even tell their families if they test positive,” said Wong.

小题1:We can conclude from the underlined sentence in the last paragraph that ______.

A.The official data always tell lies and cheat people to hide the truth.

B.3.9 million people in Singapore suffered from AIDS.

C.Singapore has a population of 3.9 million

D.The number of people infected with HIV is at least eight times larger than that of the AIDS patients in Singapore.小题2:It is judged that there are ______ people hit by AIDS in Asia or so.

A.4.3 million

B.6 million

C.8 million

D.3.7 million小题3:According to the passage, the main reasons that AIDS spread in Asia is through_______. 

A. blood

B.unsafe sex

C.love

D.drugs小题4:Which of the following statements is not right?     

A.The battle against Aids in many Asian countries is against their culture and

social customs.

B.Though the HIV infection in Asia develops with low speed, the infected number

is still quite large compared to other continents.

C.India has the second largest number of HIV infected people.

D.Aids might affect the poverty-stricken countries more severely.

单项选择题