问题 选择题

金星是离地球最近的一颗行星,它是一个被浓密的大气层包围的固体球,三氧化二碳(C2O3)是金星大气层的成分之一,化学性质与一氧化碳相似.下列有关三氧化二碳的说法不正确的是(  )

A.C2O3具有还原性

B.C2O3充分燃烧的产物是CO2

C.C2O3属于氧化物

D.C2O3中碳元素的质量分数约为66.7%

答案

A、根据CO具有还原性,而三氧化二碳化学性质与一氧化碳相似,可判断C2O3具有还原性;故A正确;

B、根据CO具有可燃性,在氧气中燃烧生成二氧化碳,三氧化二碳化学性质与一氧化碳相似,可判断C2O3充分燃烧的产物是CO2;故B正确;

C、C2O3由碳氧两种元素组成,属于氧化物;故C正确;

D、C2O3中碳元素的质量分数=

12×2
12×2+16×3
×100%≈33.3%;故D不正确.

故选D.

阅读理解

Most rain forests lie close to the equator(赤道),where the climate is often mild and there are long hours of sunshine.The warmth of the land heats the air above,causing it to rise and tiny drops of water to fall as rain.The rainfall can reach at least 98 inches a year.This wet,warm world with plenty of sunlight is perfect for plants to grow,so the trees grow fast with green leaves all the year round.The trees themselves also have an effect on the climate.They gather water from the soil and pass it out into the air through their leaves.The wet air then forms clouds,which hang over the treetops like smoke.These clouds protect the forest from the daytime heat and night-time cold of nearby deserts,keeping temperatures fit for plant growth.

Rain forests slightly farther away from the equator remain just as warm,but they have a dry season of three months or more when little rain falls.Tree leaves fall during this dry season and new leaves grow when the wet season or monsoon(雨季) begins.Thus these areas are known as the “monsoon forest”.

Another type of rain forest grows on tropical mountains.It is often called the “cloud forest” because clouds often hang over the trees like fog.

The rain forest is the ideal place for the growth of many different trees.Most of them depend on animals to eat their fruits and spread their seeds.When the fruits are eaten,the seeds inside them go undamaged through animals’ stomachs and are passed out in their droppings.The seeds lying on the forest floor then grow into new trees.

小题1:The climate of the rain forests near the equator is _______.

A.mild,wet and windy

B.hot,rainy and foggy

C.hot,wet and cloudy

D.warm,wet and sunny小题2:We can learn from the passage that _______.

A.tree leaves are green all the time in the monsoon forest

B.there is a dry season in the cloud forest on tropical mountains

C.clouds help the plants in the rain forest near the deserts to grow

D.the formation of climate in the rain forest has little to do with the trees小题3:According to the passage,_______ play the most important role in the spreading of seeds.

A.animals

B.droppings

C.fruits

D.winds小题4:This passage is most likely to be found in _______.

A.a travel guide

B.a story book

C.a technical report

D.a geography book

多项选择题