问题 选择题

鉴别H2SO4、CaCl2、NaCl三瓶无色溶液,可选用的试剂是(  )

A.Na2CO3

B.BaCl2

C.紫色的石蕊试液

D.AgNO3

答案

A、向三种溶液中分别加入碳酸钠溶液,若有气泡冒出的则是稀硫酸;若有沉淀生成的则是氯化钙;若无明显现象的则是氯化钠.故A能鉴别;

B、向三种溶液中分别加入氯化钡溶液,若有白色沉淀生成的则是稀硫酸;若无明显现象的则是氯化钙溶液和氯化钠溶液.用氯化钡不能鉴别出氯化钙和氯化钠.故B不能鉴别;

C、向三种溶液中分别加入紫色的石蕊溶液,若溶液变红的则是稀硫酸,若无明显现象的则是氯化钙溶液和氯化钠溶液.用石蕊溶液不能鉴别出氯化钙和氯化钠.故C不能鉴别;

D、向三种溶液中分别加入硝酸银溶液,若有白色沉淀生成的则是氯化钙和氯化钠,若无明显现象的则是稀硫酸.用硝酸银溶液不能鉴别出氯化钙和氯化钠.故D不能鉴别.

故选A

判断题
阅读理解

Ellis Island is located in New York. Harbor Ellis Isl and is open daily year-round from 9:30 a.m. to 5 p. m. , with extended hours during summer. It is closed December 25. There is no admission charge to Ellis Island; donations(捐款)are gratefully accepted.

At Your Fingertips

Park information      (212)363-7620

Emergencies         (212)363-3260

Ferry boat information  (212)269-5755

Lost and found          (212)363-7620

Dining, gifts, & audio tour (212)344-0996

Transportation

Statue of Liberty a nd Ellis Island Ferry: Boats leave from Battery Park, Manhattan, and from Liberty State Park, New Jersey. They run about every 30 to 45 minutes beginning at 9:15 a. m. (ferry schedule subject to change)

Hours: May vary; call the number below

Closed: December 25

Ferry fees: (Includes Liberty and Ellis Islands) adults, $7; senior citizens, $6; children(age 3 to 17), $3. (group rates are available for 25 or more adults)

Ticket & schedule information:    (212)269-5755

小题1:Which number would you call if your friend were suddenly ill?

A.(212)344-0996

B.(212)363-7620

C.(212)363-3260

D.(212)269-5755小题2:Which of the following is not true?

A.People can visit Ellis Island free of charge.

B.The boats departure time is at 9:15 a.m. all the year round.

C.Ferry fees for children are cheaper than for adults.

D.Ferry fees for group visitors can be reduced.小题3:We may infer from the passage that _________.

A.visitors prefer to go to Ellis Island by boat

B.there are more visitors in winter

C.Ellis Island is open every day

D.Boat is the only transportatio n to Ellis Island