问题 填空题

饲养观赏鱼,可以陶冶人的情操,增加人们对生活的热爱.空运观赏鱼,必须密封,为了解决鱼的吸氧问题,可在水中加入过氧化钙(化学式:CaO2).过氧化钙与水反应的化学方程式:______.过氧化钙中氧元素与钙元素的质量比是______.

答案

过氧化钙与水反应生成氢氧化钙和氧气,反应的化学方程式为:2CaO2+2H2O═2Ca(OH)2+O2↑.

过氧化钙中氧元素与钙元素的质量比是(16×2):40=4:5.

故答案为:2CaO2+2H2O═2Ca(OH)2+O2↑;4:5.

单项选择题
单项选择题

Emotion is a feeling about or reaction to certain important events or thoughts. People enjoy feeling such pleasant emotions as love, happiness, and contentment. They often try to avoid feeling unpleasant emotions, such as loneliness, worry, and grief.
Individuals communicate most of their emotions by means of words, a variety of sounds, facial expressions, and gestures. For example, anger causes many people to frown, make a fist, and yell. People learn ways of showing some of their emotions from members of their society, though heredity (遗传)may determine some emotional behavior. Research has shown that different isolated peoples show emotions by means of similar facial expressions.
Charles Darwin, famous for the theory of natural selection, also studied emotion. Darwin said in 1872 that emotional behavior originally served both as an aid to survival and as a method of communicating intentions. According to the James-Lange theory of emotions developed in the 1880s, people feel emotions only if aware of their own internal physical reactions to events, such as increased heart rate or blood pressure. But this theory was not up-held: by research on cats that had their nervous system damaged. The cats could not feel their body’s internal changes, but they showed normal emotional behavior. John B. Watson, an American psychologist who helped found the school of psychology called behaviorism, observed that babies stimulated by certain events showed three basic emotions--fear, anger, and love. Watson’s view has been challenged frequently since he proposed it in 1919.
The most widely accepted view is that emotions occur as a complex sequence of events. The sequence begins when a person encounters an important event or thought. The person’s interpretation of the encounter determines the feeling that is likely to follow. For example, someone who encounters a bear in the woods would probably interpret the event as dangerous. The sense of danger would cause the individual to feel fear. Each feeling is followed by physical changes and desires to take action, which are responses to the event that started the sequence. Thus, a person who met a bear would probably run away.
Several American psychologists independently developed the theory that there are eight basic emotions. These emotions--which can exist at various levels of intensity--are anger, fear, joy, sadness, acceptance, disgust,
surprise, and interest or curiosity. They combine to form all other emotions, just as certain basic colors produce all others.

Emotions are compared to colors because ______.

A. they are classified in a similar way
B. they have the same influence on people’s life
C. both of them may take on different forms
D. both of them may have basic elements mixed in them