Nguyên tố Y là phi kim thuộc chu kì 3, có công thức oxit cao nhất là YO₃. Nguyên tớ Y tạo với kim loại M hôp chất có công thức MY, trong đó M chiếm 63,64% về khối lượng. Tìm kim loại M

Chọn câu trả lời đúng:

1. Cho số hiệu các nguyên tố Mg=12, Al=13, K=19, Ca=20. Tính bazơ của các oxit tăng dần trong dãy:

A. K₂O, Al₂O₃, MgO, CaO B. Al₂O₃, MgO, CaO, K₂O

C. MgO, CaO, Al₂O₃, K₂O D. CaO, Al₂O₃, K₂O, MgO

2. Hidroxit có tính bazơ yếu nhát trong các chất sau là

A. KOH B. NaOH C. Al(OH)₃ D. Mg(OH)₂

3. Dãy sắp xếp các chất theo chiều tính bazơ tăng dần

A. NaOH, Mg(OH)₂, Al(OH)₃, Si(OH)₄ B. Si(OH)₄, Al(OH)₃, NaOH, Mg(OH)₂

C. Mg(OH)₂, NaOH, Si(OH)₄, Al(OH)₃ D. Si(OH)₄, Al(OH)₃ , Mg(OH)₂, NaOH

4. Tính axit tăng dần trong dãy

A. H₃PO₄, H₂SO₄, H₃AsO₄ B. H₂SO₄, H₃AsO₄, H₃PO₄

C. H₃PO₄, H₃AsO₄, H₂SO₄ D. H₃AsO₄, H₃PO₄, H₂SO₄

Chia động từ trong ngoặc ở thì quá khứ đơn hoặc hiện tại hoàn thành:

1. What she (do) when you (arrive) there? She (write) a letter

2. She (have) her bath while her sister (get) the breakfast ready

3. The storm (begin) at half past ten while the class (study) history

4. When the students (hear) the bell, they (get) up and (leave)

5. Mr harvey (ask) me about my plans the next time he (see) me

6. Just as I (leave) for home, a student (stop) me in the hall

7. As I (cross) the street, two cars (race) by me at full speed

8. Dorothy and I (just leave) the house when the telephone (ring)

9. The minute I (hear) the news, I (send) hima telegram

10. I (go) to ask you to help me, but you (sleep) so peacrfully when I (look) into your room that I (decide) to do it alone

11. My mother (arrive) while I (clean) the kitchen

12. John (work) from morning to night he (study) to be a doctor

13. Just as I (write) the letter, the inkpot (fall) over

14. A noise of breaking chairs (suggest) the the men (fight)

15. He (just close) the church door when he (notice) a man still praying in the corner

16. The men (fight) bravely, but the general (order) them to retreat

17. As he (come) up to his house in the darkness, he (see) that a man (climb) out of one of the bedroom windows

18. John (work) hard when suddenly the door (open)

19. When we (open) the front of door we (see) someone walking out of the gate

20. Lightning (strike) the tree that they (shelter) under. Of course, they (have) a terrible fright, but they (be) very lucky. No harm (come) to them at all

Điền động từ thích hợp cho câu theo thì hiện tại đơn hoặc hiện tại hoàn thành:

1. My father often (go) to the theatre but my mother (not go) very often. He (like) all sorts of plays. She (prefer) comedies

2. I usually (go) home by train, but this weekend I (go) by bus. It (take) longer but it (cost) less

3. John (take) a group of American tourists round now and tomorrow an Australian group (come)

4. The boy (not brother) to knock at the door, but the girl always (knock)

5. They (enjoy) it, but they (not understand) some of the jokes

6. Look! The policeman (put) a ticket on Tom's cat. Tom will be furious when he (see) it. He (hate) getting parking tickets

7. All the guides here (speak) at least three foreign languages, because a lot of foreign visitors (come) every summer

8. An (make) a dress for herself at the moment. She (make) all her own clothes

9. My wife usually (do) the shopping, but I (do) it today as she isn't well

Chia thì quá khứ của động từ trong ngoặc

1. He (do) nothing before he saw me

2. He thanked me foe what I (do)

3. I (be) sorry that I had hurt him

4. After they had gone, I (sit) down and (rest)

5. As soon as you (go), I (want) to see you again

6. Before you (go) very far, we found that we (lose) our way

7. He (die) after he (be) ill a long time

8. My friend (not see) me for many years when I met him

9. In England he soon remembered all he (learn)

10. When the airplane landed, the pilot (find) that one of the wings (be damaged) by a shell

Complete the following sentences with me Simple Present, the Present Continuous or the Present Perfect tense

1. Listen! I (think) someone (knock) at the door

2. Mr Smith (pay) all og his bills at the end of the month

3. Michael (study) English for six month now

4. It usually (rain) very much in that part of the country

5. I (be) sorry. I (forget) that fellow's name already

6. My secretary (sit) at a different desk today

7. Our present boss (work) in this company all of his life

8. Up to the present, Geogre (do) good work in this class

9. So far, you (make) no mistakes on this exercise

Chọn câu trả lời đúng:

1. He....in London for two years and then....to Paris

A. has lived/has gone B. lived/went C. has lived/went D. lived/has gone

2. You......your hair long when you.....at school?

A. Did you wear/are B. Did you wear/were C. Do you wear/were D. Do you wear/have been
3. Tom....to England two years ago. He....there for a while and then....to Canada

A. went/worked/went B. went/has worked/went

C. went/has worked/has gone D. went/was working/went

4. I....tennis when I was at shcool. I...it very much

A. play/enjoy B. played/enjoyed C. played/enjoy D. have played/enjoyed

5. I....on the train, you know. Why do you keep asking to see my ticket? I....it to you three times in the last four hours

A. didn't just get/already showed

B. didn't just get/have already showed

C. haven't just got/already showed

D. haven't just got/have already shown

Đặt các động từ vào thi hiện tại hoàn thành:

1. I (work) very hard for this exam

2. You (be) to the zoo?

3. I'm afraid you (look) at the wrong one

4. Why are the police here? What (happen)?

5. Please stay for dinner. Jane (cook) a lovely meal

6. This watch was working all right a moment ago but now it (stop)

7. Lunch is not quite ready yet, although I (cook) all the morning

8. Look! That light (burn) all night

Chọc câu trả lời đúng:

1. I (see/am seeing) that the situation is out of control

2. The sausages (are tasting/taste) delicious

3. (Do you enjoy/Are you enjoying) this party?

4. You haven't said a word all morning. What (are you thinking/do uou think) about?\

5. He (has/is having) a Siamese cat

6. These flowers are (smelling/smell) nice

7. I (don't know/am not knowing) where she keeps the keys

8. Why (are you feeling/do you feel) your pockets? Hve you lost anything?

9. Why (do you smell/are you smelling) the milk? Do you think it has gone off?

10. Anna is Italian. She (is coming/comes) from Italy

11. That dress (looks/is looking) nice on you

12. Paul (listens/is listening) to a new record in his room

Điền thì hiện tại hay tiếp diễn:

A: What.......(you/do) now?

B: I.....(look) through these old film magazines. Look, here's an old picture of Jack Nicholson

A: Oh, I.....(think) he.....(look) awful! And his suit.....(not/fit) him properly

B: Yes, I.....(agree). And he.....(appear) to be really angry. I wonder what he....(think) about

A: He....(be) in that new film that's on at the Odeon now, isn't he?

B: Yes, I saw it last night. He.....(look) very different now. He.....(weigh) a lot more

A: I.....(hope) it's a good film. I....(see) it tonight. Stuart....(take) me. Actually, he.....(be) very nice to me these days

B: He probably....(want) to borrow some money

A: I....(see). That explains it

Nguyên tố M thuộc nhóm IIA trong công thức oxit của M. Trong đó oxi chiếm 40% khối lượng. Tìm nguyên tố M

Oxit cao nhất của một nguyên tố là RO₂. Trong đó R chiếm 27,27% khối lượng. Tìm R là nguyên tố nào

Bài 1: Tỉ khối của hỗn hợp X gồm oxi và ozon so với He là 9. Tính thành phần % theo thể tích của oxi và ozon