问题 计算题

钙是人体中含量较高的常量元素之一,缺钙可能导致幼儿及青少年发育不良,严重时还会患佝偻病。李明的父亲为他买回一瓶补钙保健品,他仔细阅读了标签上的说明(如图)。为了验证该保健品中碳酸钙的含量,取出5片药品,加入足量的稀盐酸,充分反应后收集到3.3g二氧化碳(假定除碳酸钙外,其他成分不与盐酸反应)

【净含量】2g×200片
【主要原料】碳酸钙(质量分数≥70%)
【使用方法】每日两次,一次一片,嚼食
(1)已知碳酸钙的相对分子质量是100,则钙元素的相对原子质量为____________。(2)通过计算验证:该保健品主要原料含量是否属实(写出计算过程)?(3)李明按照说明服用一个月(30天),理论上吸收了钙元素_____克。

答案

(1)40

(2)解:设每5片药片中含碳酸钙的质量为x

CaCO3+2HCl===CaCl2+H2O+CO2

  100                                     44

    x                                      3.3g

100:44=x:3.3g,

解得x=7.5g

所以药品中碳酸钙的质量分数是7.5g/(2g×5)×100%=75%

通过计算得出碳酸钙的质量分数是75%,大于70%,所以该保健品主料含量标注属实。

(3)36

阅读理解

阅读理解

     Vans, Keds, Dollies-they sound like the names of rock bands, but if you have teenagers, you'll know

they're actually the latest in teenage footwear.

     But experts are now warning that the current shoe fashions will be causing teenagers discomfort in the

short term and storing up years of foot, knee and back pain in the future.

Here, the experts identify the problems caused by teenagers'shoe choice.

KEDS/VANS

     Slipon shoes with elastic (弹性的) sides are particularly popular among teenage boys-with Keds and

Vans the most soughtafter brands.

     The main problem is that they are just too flat-so flat that the heel, which strikes the ground first,

becomes damaged and painful.

BALLET PUMPS

     The worst shoes of all are such light and thin dolly shoes.The problem is partly their flatness, as with

Keds and Vans.However ballet pumps, which  have no string or heel, have other specific problems.

     "As the shoe has no fastening device, it relies on the toes to keep the shoe on, causing an awkward

gait (步法), this leads to shortand longterm problems such as calluses (茧子), heel and knee pain."

WEDGES AND STILETIOS

     These shoes can also cause problems with gait.They may look good, but the heels on these are so high they can force the wearer's body weight forward, making them very unstable.

     Teens who wear these shoes regularly are also in danger of joining those millions of women with

constant back pain.

SCHOOL SHOES

     So what do podiatrists (足科医生) have on their wish list, especially for everyday wear?

     Something in a natural, breathable fabric, with a string to hold it on, with a small heel and a deep toebox that does not press the toes, such as Clark's, Marks & Spencer or Rhino.

     If your teen insists on wearing 'bad'shoes, get them some simple foot orthotics (矫形器) in the shoes.

These support and correct the movement of the foot and, properly fitted by a podiatrist, can often

transform their walk and halt the damage.

1. Of all the shoes mentioned in the passage, which can cause the worst problems?

A. Marks & Spencer.  

B. Wedges & Stilettos.

C. Keds and Vans.  

D. Ballet Pumps.

2. Which pair of shoes may not be found on the podiatrists'wish list?

3. The underlined word "halt" in the last paragraph probably means________.

A. increase  

B. worsen  

C. stop  

D. cure

4. From this passage we can infer________.

A. trendy shoes may ruin teenagers' health

B. fashionable shoes all have orthotics in them

C. experts are strongly against wearing popular shoes

D. podiatrists are experts at producing branded shoes

5. In which column of Mail Online can you find this passage?

A. Sports.  

B. Science.  

C. Health.  

D. Shopping.

单项选择题