问题 多选题

下列说法中不正确的是(  )

A.质子数相同的微粒一定属于同一种元素

B.质子数相同,电子数也相同的两种微粒,不可能是一种分子和一种离子

C.电子数相同的微粒不一定是同一种元素

D.一种元素只能有一种质量数

答案

A、具有相同质子数的原子一定属于同种元素,但微粒可能为原子、分子、离子等,如Na+、NH4+的质子数都是11,HF、Ne的质子数都是10,但不是同种元素,故A错误;

B、分子中质子数=电子数,而离子中质子数≠电子数,若两粒子中质子数相同,电子数肯定不同,所以质子数相同,电子数也相同的两种粒子,不可能是一种分子和一种离子,故B正确;

C、同种元素具有相同的核电荷数(即核内质子数),电子数相同的微粒不一定是同一种元素,如K+和Ca2+,具有相同的电子数,但不是同种元素,故C正确;

D、原子的质量数=质子数+中子数,而同一元素的质子数相同,中子数可能不同,所以同种元素的原子其质量数不一定相等,故D错误;

故选AD.

阅读理解

A desert is a very dry land where there is hardly any rain. In the day, it can be so hot that you could fry an egg on the ground. But during the night it is sometimes so could that water would turn into ice.

Many desserts are covered in sand. But some have mountains, rocks, or lakes that have dried up in the heat. The Great American Dessert has cliffs(悬崖) that have been made into amazing and beautiful shapes by the wind. The Sahara Desert in Africa is mostly sand. The Australian Desert has red sand.

Sometimes it does not rain for a whole year in the desert. But there is water deep under the ground and some plants have roots that go very deep to find it. Other plants have roots that spread out(延伸) a long way so they can suck up the rain as soon as it falls.

One desert plant is the cactus, which has long, spreading roots. The cactus stores water inside its hard skin. This skin protects it from heat and cold.

Camels are a bit like cactus plants! They store water too—inside their bodies. They have special fur which protects them from the sun during the day and keeps them warm at night.

Some other animals live in deserts, too. They have to be very good at seeing and hearing because most of them only come out at night. This is why many desert animals have extra big eyes or ears.

A desert fox has bigger ears than a normal for. A gerbil has huge eye, so that it can see at night. It stays cool in the day by staying underground, like most desert animals.

Some people live in the desert but they always make their homes near an oasis. An oasis is where water comes from an underground river. Near an oasis, people can grow lots of plants and keep animals.

Life is hard in the desert, for people, animals and plants. But desert people like to live there.

小题1:A desert is very dry because__________.

A.it is sandy

B.there is so little rain

C.the wind is strong

D.there is no water deep under the ground小题2:What does the underlined phrase"suck up"in paragraph 3 mean_________?

A.围堵

B.讨好

C.释放

D.吸收小题3:Some desert animals have extra big eyes or ears because__________.

A.the sunlight is too strong in the day

B.they need to see and hear well at night

C.it is very cold at nigh

D.they store water in them.小题4:Most desert animals stay cool in the day by_________.

A.storing water in side their bodies

B.drinking water as much as they can

C.staying underground

D.growing lots of plants小题5:Which of the following is true?

A.Desert people like to live in the desert though life is hard.

B.People in the desert usually fry eggs on the ground.

C.Camels have special fur to store water.

D.All the deserts are covered in sand.

单项选择题