一种可作为绿色能源的物质X,其燃烧的化学反应为:X+2O2→CO2+2H2O,判

题型:选择题

问题:

一种可作为绿色能源的物质X,其燃烧的化学反应为:X+2O2→CO2+2H2O,判断X的化学式为(  )

A.H2

B.CH4

C.CH3OH

D.C2H5OH

考点:质量守恒定律
题型:选择题

用氢氧化钠溶液测定某硫酸溶液溶质的质量分数.实验如下:取25g该硫酸溶液,加入到烧杯中,然后把50g质量分数为10%的氢氧化钠溶液不断滴入烧杯中,同时用电子PH计不断读取反应时的PH,得出如图所示的关系,求;

(1)该硫酸溶液溶质的质量分数.

(2)配制500g上述硫酸溶液,所需质量分数为98%的硫酸溶液的质量.

题型:选择题
信息匹配(1分X5=5分)
Shanghai is not only the largest seaport city and economic(经济的) center of China, but also the most modern and fashionable international(国际的) city as well. It lies in the east of China and faces the East China Sea.
With a long history, there are many interesting places in Shanghai. It is really a good place to go on vacation. Also being a modern city, Shanghai is a good place to go shopping. You can see many fashionable things there. Walking along Nanjing Road and Huaihai Road, you will have a chance to follow the latest fashion.
I think the best time to Shanghai is in summer. But don’t forget to bring your umbrella because it rains a lot here in summer.
Welcome to Shanghai!
The location(地点) of Shanghai
1. It lies in _____________ and faces the East China Sea.
What to do in Shanghai?
2. Visit _____________.
3. _____________________________.
Two famous roads in Shanghai
4. ________________ and Huaihai Road.
What’s the weather like in summer in Shanghai?
5. It___________________ in summer.
题型:选择题

清朝康熙末年,人口只有两三千万,乾隆年间增至三亿多,导致人口猛增的主要原因是

A.粮食产量提高  

B.疆域扩大

C.推行"摊丁入亩"

D.耕地面积增加

题型:选择题

准确确定刀具在加工过程中每一位置所需的数据称为()数据。

A.切削点

B.切触点

C.刀尖点

D.刀位点

题型:选择题

DL/T438-2009规定:机组第一次A级检修或B级检修,应按()%对管件及阀壳进行外观质量、硬度、金相组织、壁厚、椭圆度检验和无损探伤。

A、10%

B、20%

C、100%

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