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问题 多选题

设NA是阿伏加德罗常数的数值，下列说法正确的是（　　）

A．常温下，23 g NO2含有NA个氧原子

B．1 mol Cl2与足量的铁反应，转移的电子数为3NA

C．0.1 mol24Mg32S晶体中所含中子总数为2.8 NA

D．用惰性电极电解硫酸铜溶液，若生成1 mol O2，则转移电子数为2NA

答案

A、23 g NO2物质的量=

23g
46g/mol
=0.5mol，含有NA个氧原子，故A正确；

B、1 mol Cl2与足量的铁反应，1mol氯气全部反应转移的电子数为2NA，故B错误；

C、0.1 mol24Mg32S晶体中所含中子总数=0.1mol×（24-12+32-16）×NA=2.8 NA，故C正确；

D、用惰性电极电解硫酸铜溶液，若生成1 mol O2，依据电极反应电子守恒，阳极电极反应4OH--4e-=2H2O+O2↑则转移电子数为4NA，故D错误；

故选AC．

单项选择题

城市桥梁工程大体积混凝土浇筑时，产生裂缝的原因不包括( )。

A．桩身混凝土强度低

B．水泥水化热引起的温度应力和温度变形

C．外界气温变化的影响

D．内外约束条件的影响
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填空题

Motivation is "the driving force within individuals that impels them to action." And goals are the sought-after results_____(1) motivated behavior.Motivation can be either positive or negative_____(2) direction. We may feel a driving force toward some object or condition, _____(3) a driving force away from some object or condition. For example, a person may be impelled toward a restaurant to fulfill a need, hunger, and away_____(4) an airplane to fulfill a need of safety. Some psychologists refer to positive drives_____(5) needs, wants or desires,_____(6) negative drives as fears or aversions._____ (7), though negative and positive motivational forces seem to differ dramatically_____(8) terms of physical and sometimes emotional activity, they are basically similar in_____(9) they both serve to initiate and sustain human behavior.____(10) this reason, researchers often refer _____(11) both kinds of drives or motives as needs, wants and desires.Goals, _____(12), can be either positive or negative. A positive goal is one toward_____ (13) behavior is directed and it is often referred to as an approach object. A negative goal is _____(14) from which behavior is directed away and it is sometimes referred to as an avoidance object. Since both approach and avoidance goals can be considered objectives of motivated behavior, most researchers refer to_____(15) types simply as goals. Consider this example. A middle-aged woman may wish to remain_____(16) attractive as possible. Her positive goal is to appear desirable, and_____(17) she may use a perfume advertised to make her irresistible. A negative goal may be to prevent her skin_____(18) aging, and therefore she may buy and use face creams._____(19) the former case, she uses perfume to help her achieve her positive goal — attractiveness; in the____(20) case, she uses face creams to help avoid a negative goal — wrinkled skin.
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