问题 选择题

在“比较质量相等的不同燃料充分燃烧时放出的热量”的活动中,小明发现分别使5g的酒精和5g的碎纸片充分燃烧后,被它们加热的各100g、25℃的水的温度分别上升到80℃和45℃,这说明

A.燃烧酒精总比燃烧碎纸片放出的热量多

B.酒精含有的热量比碎纸片大得多

C.酒精的内能比碎纸片内能大得多

D.酒精的热值比碎纸片的热值大

答案

答案:D

题目分析:热值是燃料的一种特性,是指1kg燃料完全燃烧放出的热量;反映了燃料燃烧时产生热量方面的差异。5g的酒精和5g的碎纸片充分燃烧后,产生的热量被水吸收,水升温分别为55℃、20℃,反映了酒精燃烧产生的热量较多,酒精的热值比碎纸片的热值大;D符合题意,选填D;由Q=mq可知,燃料燃烧产生热量的多少不仅与热值有关,还与燃烧燃料的质量有关,热值大的燃料燃烧放出的热量不一定大,A错;热量是个过程量,是在能量转化或转移过程中表示能量增加或减少的量,物质具有的能量用内能来表示,B错;内能的大小与物质的种类、温度、质量、状态等有关,C错。

问答题 简答题
阅读理解

How to be Prepared

Electricity, water, gas and telephone may not be working after an earthquake. The police and fire department are likely to be tied up. You should be prepared to take care of yourself for at least three days, preferably for a week.

This list can also be applied to other disasters, such as floods or wildfires.

1. food and water (a gallon a day per person)

2. a first aid kit

3. a fire extinguisher suitable for all types of fires

4. flashlights, a portable radio extra batteries

5. blankets, clothes, shoes and money (ATMs may not work)

6. baby and pet food

It’s also a good idea to decide beforehand how and where your family will reunite if separated during a quake and to conduct in-home practice drills.

During an Earthquake

If you are indoors, stay there. Get under and hold onto a desk or table, or stand against an interior wall. Stay away from exterior walls, glass, heavy furniture, and stay away from windows and outside walls and do not use the elevator.

If you are outside, get into the open, stay into the open, stay away from buildings, power lines or anything else that could fall on you.

If you are driving, move the car out of traffic and stop, avoid parking under or on bridges or overpasses, Try to get clear of trees, light posts, signs and power lines.

If you are in a crowded public place, avoid panicking and do not rush for the exit. Stay low and cover your head and neck with your hands and arms.

After an Earthquake

If the phone is working, only use it in case of emergency. Likewise, avoid driving if possible to keep the streets clear for emergency vehicles.

Be aware that items may fall out of cupboards or closets when the door is opened, and also that chimneys can be weakened and fall with touch. Check for cracks and damage to the roof and foundation of your home.

Listen to the radio for important information and instructions. Remember that aftershocks, sometimes large enough to cause damage in their own right, generally follow large quakes.

If you leave home, leave a message telling friends and family your location.

小题1:Which of the following items is unnecessary to prepare before an earthquake?

A.Batteries

B.Cash

C.Medicine

D.Creditcard小题2:When an earthquake comes,you should ______. 

A.hideyourselfinthekitchen

B.rushfortheexitimmediately

C.stayawayfromheavyobjects

D.callthepolicerightaway小题3:When an earthquake is over,you should______. 

A.driveacartotakeyourfamilytothesafeplace

B.checkthesecurityofyourhome

C.callyourrelativestotellthemyouaresafe

D.clearupthemessassoonaspossible.小题4:Which of the following sentences is true according to the passage? 

A.You’dbettermakeitclearhowandwhereyourfamilywillreuniteifseparatedduringaquakeafterthequakehappens.

B.Ifyouareindoors,getintotheopen.

C.Ifyouareinacrowdedpublicplace,avoidpanickinganddorushfortheexit.

D.Ifthephonestillworks,onlyuseitwhennecessary.小题5:What does the underlined word “aftershock ” mean? 

A.Alessseriousquakefollowingalargeearthquakeinthesamearea.

B.Afurtherreactionfollowingtheshockofadeeplydisturbingthing.

C.Amessonehastodealwithafteraterriblething.

D.Aninstructionthegovernmentgivestosolveproblems.