问题 实验题

实验室中有一瓶标签破损的固态铵盐,它可能是NH4Cl、NH4NO3、NH4HCO3、(NH4)2SO4中的一种,请利用下图所示的溶液进行实验探究.

(1)【提出猜想】

猜想①:该铵盐是NH4Cl

猜想②:该铵盐是          

猜想③:该铵盐是NH4HCO3

猜想④:该铵盐是(NH4)2SO4

(2)【实验探究】

步骤一:取少量样品放入试管中,没有嗅到强烈的氨味,加入适量水溶解得到无色液体,选用图中的                       溶液滴入试管中,无气泡放出,则猜想③不成立

步骤二:在步骤一所得的溶液中,滴加图中的Ba(NO3)2溶液,没有白色沉淀生成,则猜想            不成立

步骤三:另取适量样品放入试管中,加水溶解配成溶液,滴加图中的           溶液,有白色沉淀生成,则猜想                 成立.

(3)【拓展应用】

铵盐可作氮肥,它会与碱性物质发生化学反应,请写出硝酸铵溶液与氢氧化钠溶液在加热条件下反应的化学方程式                                           ,所以在农业生产中,为避免降低肥效,铵态氮肥不要与碱性物质混合施用

答案

(1)NH4NO3

(2)步骤一:稀盐酸(或HCl)

步骤二:④

步骤三:硝酸银;①

(3)NH4NO3+NaOH=NaNO3+NH3↑+H2O

不定项选择
阅读理解

The dirty, homeless man sat on the pavement, staring at the stones. He thought back more than twenty years to when he was a boy living in a small red brick house on this very street. He recalled the flower garden, the swing his dad made, and the bike he had saved up for months to buy.

The man shrugged impatiently, for the brightness of those pictures hurt him, and his memory traveled on another ten years. He had a job by then, plenty of friends and started to come home less. He did not really want to remember those years, nor the day when, because of debts, he had gone home planning to ask for money. He felt embarrassed, but he knew exactly where his dad kept the money. When his parents stepped out of the room, he took what he wanted and left.

That was the last time he had seen them. Ashamed, he went abroad, and his parents knew nothing about the years of wandering or time in prison. But locked in his cell he often thought of home. Once free, he would love to see his parents again, if they were still alive, and still wanted to see him.

When his prison time was up, he found a job, but couldn’t settle. Something was drawing him home. He did not want to arrive penniless, so he hitchhiked most of the long journey back. But less than a mile from his destination he started to feel sick with doubt. Could they ever accept this man who had so bitterly disappointed them?

He spent most of that day sitting under a tree. That evening he posted a letter which, although short, had taken him hours to write. It ended with:

I know it is unreasonable of me to suppose you want to see me ... so it’s up to you. I’ll come early Thursday morning. If you want me home, hang a white handkerchief in the window of my old bedroom. If it’s there, I’ll come in; if not, I’ll wave good-bye and go.

And now it was Thursday morning and he was sitting on the pavement at the end of the street. Finally he got up and walked slowly toward the old house. He drew a long breath and looked.

His parents were taking no risks. ________________________________________

The man threw his head back, gave a cry of relief and ran straight through the open front door.

小题1:Why did the man shrug impatiently (paragraph 2) while he was thinking of his childhood?

A.The thoughts made him angry.

B.He felt he had wasted time.

C.He was anxious to go home.

D.The sweet memory caused him much pain.小题2:Why did it take him hours to write the letter?

A.He doubted if his parents still lived in that house.

B.He had much news to tell his parents.

C.He felt ashamed to ask for forgiveness.

D.He was longing to return home and felt excited.小题3:In what order did the following events take place?

a. He took the money from his parents.

b. He bought a bicycle with his savings.

c. He was sentenced to prison.

d. He wrote the letter home.

e. He sat on the pavement.

f. He hitchhiked back home.

A.b, a, c, d, e, f

B.b, a, c, f, d, e

C.a, c, b, d, f, a

D.a, d, b, c, e, f小题4:Which of the following best fits into paragraph 8?

A.Every inch of the house was covered in white. Sheets, pillowcases and table clothes had been placed on every window and door, making it look like a snow house.

B.The house before him was just as he remembered: the red bricks, the brown door and nothing else.

C.A colorful blanket was over the front door. On it, in large letters, was written, “Welcome home, son”.

D.A police car was parked in the drive way, and two officers stood at the front door.小题5:The best title of the passage is _______.

A.Sweet Memory

B.White Handkerchief

C.Abandoned Son

D.Leaving Home