问题 填空题

X、Y、Z为周期表中前20号主族元素,原子序数递增,X、Y原子的最外层电子数是其电子层数的2倍,Z是人体含量最高的金属元素。

(1) 下列含氧酸根化学式书写不正确的是________ (填序号)。

a.XO3-  b.XO32-  c.YO32-  d.Y2O32-  e. X2O42-   f. XO42-

(2) Y的最高价含氧酸是重要的化工产品。

①实验测得相同条件下一定量的Y单质分别在空气和在氧气中充分燃烧后产物的成分(体积分数)如表。

Y在纯氧中燃烧产物里YO3含量比空气中少的原因是__________。

②天然ZYO4既可用于制备Y的氧化物又可用于制水泥。ZYO4与X单质在高温下反应,得到两种常见气体。每消耗1 molX单质,有4 mol电子转移,该反应的化学方程式是:_______________。

(3) 为了测定某水泥样品成分,称取10.0g样品,将其中的Z元素转化为ZX2O4沉淀,将沉淀用稀酸处理得H2X2O4溶液,取该溶液体积的1/100,用KMnO4溶液滴定(氧化产物为XO2,还原产物为Mn2+),结果用去0.0200 mol·L-1。的KMnO4溶液24.00mL。该样品中Z的氧化物的质量分数是_________。

答案

(1)a f

(2)①纯氧中,O2浓度大,单位时间内放热多,体系温度高,平衡向SO3分解的方向移动。

(3)67.2%

阅读理解

阅读理解。

     

     On a very hot day, it is hard to know what to do to feel good. If you run around, you may feel sick in

your stomach. However, if you just sit quietly and do nothing, you may feel bored. Are there things you

can do to feel good and have fun when you're hot?

     Perhaps playing in water is a good choice to make you cool down. Taking a cool bath or shower, or

even washing toys in a pan of cool water can also make you feel good on a hot day. Besides, you can read

stories or paint in front of a fan. You don't need to move your body very much. These are just some of the

cool things to do on a hot day.

     In addition, it's important for you to drink water. On hot days, you can lose about 16 glasses of water

in one day. If you feel thirsty, you are already short of water. So don't wait for thirst before you start to

drink. You should try to drink as much water as you lose every day. Mixing a little fruit juice into your

water is a fun way to help you drink plenty of water.

     The food you eat also makes a difference in how you feel in the heat. Cold foods such as ice cream and

drinks with some ice can cool down your bodies. Fruits and vegetables are also helpful to stay cool in hot

weather. So plan a healthy menu for a hot day---one that doesn't need any cooking.

1. Is it easy to know what to do to feel good on a hot day?

    _________________________________________________ 

2. Is playing in water a good choice or a bad one? 

    _________________________________________________ 

3. How much water do we lose one day in hot weather? 

    _________________________________________________ 

4. What is a healthy menu for a hot day?

    _________________________________________________ 

5. What is the writer's purpose of writing this passage? 

    _________________________________________________ 

单项选择题