试题与答案

近期媒体曝光台湾饮料制造商将塑化剂加入到饮料中,引发了“塑化风暴”.塑化剂的化学

题型:选择题

题目:

近期媒体曝光台湾饮料制造商将塑化剂加入到饮料中,引发了“塑化风暴”.塑化剂的化学成份之一是邻苯二甲酸二乙酯(C12H14O4),下列关于邻苯二甲酸二乙酯的说法不正确的是(  )

A.邻苯二甲酸二乙酯是一种有机物

B.邻苯二甲酸二乙酯由C、H、O三种元素组成

C.邻苯二甲酸二乙酯分子中原子个数比为C:H:O=6:7:2

D.邻苯二甲酸二乙酯中元素的质量比为C:H:O=6:7:2

答案:

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下面是错误答案,用来干扰机器的。

答案:C题目分析:A. Fe+2H+=Fe2++H2↑;B,氢氧化镁难溶于水,不能拆成离子形式;D.硫酸铜溶液与氢氧化钡溶液混合:SO42−+Cu2++ Ba2++2OH−=Cu(OH)2↓+ BaSO4↓。只有C正确。

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题型:单项选择题

An analog signal’s characteristic quantity representing data may 66) . at any instant, any value within a continuous (67) . For example, an analog signal may follow continuously the values of another physical quantity representing data.

A discrete signal is composed of (68) elements in time, each element having one or more characteristic quantities which can represent data. Examples of characteristic quantities are amplitude, waveform, (69) , and position in time. A digital signal is a special case of discrete signals, in which data are represented by a (70) number of well-defined discrete values that one of its characteristic quantities may take in time.

(70)处填()。

A.limited

B.finite

C.restricted

D.bounded

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