Hòa tan 8,4g một kim loại A hóa trị II bằng một lượng dư axit HCl thu được 3,36 lít khí H2 (đktc). Tìm kim loại A? (Cho: Cu =64; Ca =40; Mg = 24; Fe =56)

Fe

Ca

Mg

Cu

 Cho sơ đồ phản ứng sau: KClO3 → O2→X → H2. Chất X có thể là:

Na2O

H2O

Fe3O4

SO2

Xóa lựa chọn

Chất nào tác dụng được với oxi tạo ra oxit bazơ?

Lưu huỳnh

Sillic

Hiđro

Kẽm

Hai vật được làm bằng thép có khối lượng lần lượt là m1 = 1kg, m2 = 2kg. Sau một thời gian nung nóng, vật 1 thu nhiệt lượng là Q1, vật 2 thu nhiệt lượng là Q2 thì độ tăng nhiệt độ của hai vật như nhau. So sánh Q1 và Q2? Giải thích: *

A. Q2 > Q1, vì m2 > m1

B. Q1 = Q2, vì chúng được làm bằng thép.

C. Q1 = Q2, vì độ tăng nhiệt độ bằng nhau.

D. Q2 < Q1, vì m2 > m1

Chỉ viết câu = such.....that

the ice was thick. there was no danger of the skaters faling through

she look il. her parents took her to the hospital

the water was very dirty. we decided not to go swimming

Làm ơn hãy làm theo vd được ko

VD

1The walk only took five minutes

- It is a five minute walk

2 I started work for the company a year ago

- i have been working for tho company for a year

he learned to drive when he was eight

-he has

the flight to moscow lasted three and half hours

-it took

he spends two hours a week sorting out stamps

-sorting out

Lam theo vi du

VD

1The walk only took five minutes

- It is a five minute walk

2 I started work for the company a year ago

- i have been working for tho company for a year

he learned to drive when he was eight

-he has

the flight to moscow lasted three and half hours

-it took

he spends two hours a week sorting out stamps

-sorting out

Lam theo vi du

VD

1The walk only took five minutes

- It is a five minute walk

2 I started work for the company a year ago

- i have been working for tho company for a year

he learned to drive when he was eight

-he has

the flight to moscow lasted three and half hours

-it took

he spends two hours a week sorting out stamps

-sorting out

Victor has collected postage stamps for twenty years

he hasn't seen the younger son for three week /change the following sentences into passive