4.Which of the following is TRUE according to the passage?
A. 326 people were dead in mass food poisoning cases.
B. Staple foods no longer need to be checked.
C. More people suffered in food poisoning cases in 2006 than in 2007.
D. The director of Food and Drug Administration is worried about the situation.
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5.What is the main idea of this passage?
A. The city is preparing for the Olympic Games.
B. The authorities set targets for safe food and medicine.
C. People are asked to meet health requirements.
D. Management on food and medicine is difficult.
反应A+B→C的速率方程式是v=k[c(A)]1/2c(B),如果A、B浓度都增大到原来的4倍,那么反应速率将增大到原来的( )。
A. 16倍;
B. 8倍;
C. 4倍;
D. 2倍。
正反应的活化能大于逆反应的活化能时,下列关于正反应的热效应的叙述中,正确的是..( )。
A. △rHm>0;
B. △rHm<0;
C. △rHm=1/2[Ea(正)-Ea(逆)];
D. △rHm=1/2[Ea(正)+Ea(逆)]。
不影响反应速率系数的因素是( )。
A. 反应活化能;
B. 反应温度;
C. 催化剂;
D. 反应物浓度。