问题 选择题

下列说法正确的是(  )

A.铝片与烧碱溶液反应,水是还原剂

B.Na2O2与CO2反应,Na2O2是氧化剂、CO2是还原剂

C.向纯净的FeCl2溶液中滴入KSCN溶液出现血红色

D.等质量的两份铝分别放入过量的盐酸和氢氧化钠溶液中,放出的氢气的量相同

答案

A.铝片和氢氧化钠溶液的反应方程式为:2Al+2NaOH+2H2O=2NaAlO2+3H2↑,该反应中H元素的化合价由+1变为0,水为氧化剂,故A错误;

B.过氧化钠和二氧化碳的反应方程式为:2Na2O2+2CO2=2Na2CO3+O2,该反应中的过氧化钠中氧元素由-1价变为0价和-2价,所以过氧化钠既是氧化剂又是还原剂,二氧化碳既不是氧化剂又不是还原剂,故B错误;

C.亚铁离子和硫氰化钾溶液不反应,铁离子和硫氰化钾溶液生成络合物而使溶液呈血红色,故C错误;

D.铝与过量的盐酸或氢氧化钠溶液反应,生成氢气的量与铝的质量成正比,铝的质量相等,则生成氢气的量相等,故D正确;

故选D.

单项选择题

Nuclear power’s danger to health, safety, and even life itself can be summed up in one word: radiation.

Nuclear radiation has a certain mystery about it, partly because it cannot be detected by human senses. It can’t be seen or heard, or touched or tasted, even though it may be all around us. There are other things like that. For example, radio waves are all around us but we can’t detect them, sense them, without a radio receiver. Similarly, we can’t sense radio activity without a radiation detector. But unlike common radio waves, nuclear radiation is not harmless to human beings and other living things.

At very high levels, radiation can kill an animal or human being outright by killing masses of cells in vital organs. But even the lowest levels can do serious damage. There is no level of radiation that is completely safe. If the radiation does not hit anything important, the damage may not be significant. This is the case when only a few cells are hit. And if they are killed outright, your body will replace the dead cells with healthy ones. But if the few cells are only damaged, and if they reproduce themselves, you may be in trouble. They reproduce themselves in a deformed way. They can grow into cancer. Sometimes this does not show up for many years.

This is another reason for some of the mystery about nuclear radiation. Serious damage can be done without the victim being aware at the time that damage has occurred. A person can he irradiated and feel fine, then die of cancer five, ten, or twenty years later as a result. Or a child can be born weak or liable to serious illness as a result of radiation absorbed by its grandparents.

Radiation can hurt us. We must know the truth.

According to the passage, the danger of nuclear power lies in()

A. nuclear mystery

B. radiation detection

C. radiation level

D. nuclear radiation

选择题