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【单选题】
已知样本:10,8,6,10,13,8,10,12,11,7,8,9,11,9,12,9,10,11,12,12,那么频率为0.25的范围是( )。A.
5.5~7.5
B.
7.5 ~9.5
C.
9.5 ~11.5
D.
11.5 ~13.5
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参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】We wondered __________ this afternoon.
A.
whether we would have a meeting
B.
where would we have a meeting
C.
whether we will have a meeting
D.
that we would have a meeting
【简答题】下列一组有水参与的反应： ①2Na+2H 2 O=2NaOH+H 2 ↑ ②2Na 2 O 2 +2H 2 O=4NaOH+O 2 ↑ ③Na 2 O+H 2 O=2NaOH ④3Fe+4H 2 O 高温 . Fe 3 O 4 +4H 2 ⑤2H 2 O 电解 . 2H 2 ↑+O 2 ↑ ⑥2F 2 +2H 2 O=4HF+O 2 （1）其中不属于氧化还原反应的是______（填编号）． （2）...
【单选题】下列物质的分类合理的是
A.
碱性氧化物：Na 2 O、CaO、Al 2 O 3 、Na 2 O 2
B.
碱：NaOH、KOH、Ba(OH) 2 、Na 2 CO 3
C.
氧化物：Fe 2 O 3 、NO、SO 2 、H 2 O
D.
电解质：KNO 3 、Cl 2 、HCl 、BaSO 4
【单选题】Thanks for your kind help! We would have ________ lost the game!
A.
or
B.
otherwise
C.
then
D.
Therefore
【简答题】（10分）写出化学方程式，一步实现下列转变。 ①Al→NaAlO 2 ②Al 2 O 3 →AlCl 3 ③Fe(OH) 2 →Fe(OH) 3 ④Na 2 O 2 →Na 2 CO 3 ⑤Na 2 CO 3 →NaHCO 3
【单选题】【C14】
A.
as we would now say
B.
as we will now say
C.
as we would now tell
D.
ss we will tell
【单选题】The business is risky. But______we would be rich.
A.
should we succeed
B.
would we succeed
C.
might we succeed
D.
could we succeed
【单选题】【C14】
A.
as we would now say
B.
as we will now say
C.
as we would now tell
D.
as we will tell
【单选题】用高铁酸钠（Na 2 FeO 4 ）对湖水消毒，是城市饮水处理的新技术。已知反应Fe 2 O 3 + 3Na 2 O 2 ='=2' Na 2 FeO 4 + Na 2 O .下列说法正确的是
A.
Na 2 O 2 既是氧化剂又是还原剂
B.
Na 2 FeO 4 既是氧化产物又是还原产物
C.
3摩尔Na 2 O 2 发生反应，有12摩尔电子转移
D.
在Na 2 FeO 4 中Fe为+4价，只有强氧化性，能消毒杀菌
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