Hòa tan 8,8 g hỗn hợp 2 kim loại Cu và Al vào 100g dd HCl. Phản ứng kết thúc thu được 3,36 lít khí ở đktc

a/ Tính khối lượng mỗi kim loại hỗn hợp ban đầu

b/ Tính nồng độ % của dd muối tạo thành

Hãy chọn các cặp chất sau đây: H2SO4đ, P2O5, CaO, KOH rắn, CuSO4 khan để làm khô 1 trong các khí NH3, O2, CO, CO2, CL2, hỗn hợp CO2, NH3. Giải thích?

Cho hình chữ nhật ABCD (AB>BC) AH vuông góc với BD tại H,AH cắt CD tại E, và BC tại F.

Tính AH, BH, AE biết AB=8cm, BC=6cm

CMR: AH^2= HE.HF

Cho tam giác ABC vuông tại A, đường cao AH.

a) Biết AB/AC = 5/6; BC = 122cm. Tính BH, CH.

Much has been said written about the declining numbers of and disappointing lack of diversity among American college students majoring in engineering. Among the factors cited to explain this phenomenon are the lack of exposure of high school students to the very idea of engineering and the fact that many have insufficient mathematics and science background to gain entrance to engineering school, even if they do identify the profession as a possible career. This is unfortunate, for the ideas of engineering should be integrated into the curricula not only of high schools but also of middle and primary schools. Our children are being done a disservice by not being exposed properly throughout their education to engineering activities identified as such.

After all, even pre-school children have the prerequisites in their play for appreciating exactly what engineering is: design, Indeed, design is everywhere around them throughout their school day, even in their before-school and after-school activities. It need only be pointed out to them that they designing something, and therefore being engineering of sorts, in virtually everything that they do

Much has been said written about the declining numbers of and disappointing lack of diversity among American college students majoring in engineering. Among the factors cited to explain this phenomenon are the lack of exposure of high school students to the very idea of engineering and the fact that many have insufficient mathematics and science background to gain entrance to engineering school, even if they do identify the profession as a possible career. This is unfortunate, for the ideas of engineering should be integrated into the curricula not only of high schools but also of middle and primary schools. Our children are being done a disservice by not being exposed properly throughout their education to engineering activities identified as such.

After all, even pre-school children have the prerequisites in their play for appreciating exactly what engineering is: design, Indeed, design is everywhere around them throughout their school day, even in their before-school and after-school activities. It need only be pointed out to them that they designing something, and therefore being engineering of sorts, in virtually everything that they do.

1. the writer of the passage feels strongly that....
A. children should be involved in engineering activities at an early age
B. The mathematics and science courses in schools need to be modernized
C. University engineering courses ought to be upgraded
D. The education of pre-school children is being given too much important

2. The writer points out that children can, at a very early age

A. be encouraged to take part in after-school activities

B. develop an interested in scientific matters

C. make up their minds to study engineering at university

D. be influenced by their school environment

3. The writer recognizes the fact that engineering

A. is becoming less and less popular as a field of study among university students B. is only suitable for highly intelligent students

C. is a complicated subject only suitable for really mature students

D. has become one of the most popular fields of study at American universities

3. The writer recognizes the fact that engineering

A. is becoming less and less popular as a field of study among university students

B. is only suitable for highly intelligent students

C. is a complicated subject only suitable for really mature students

D. has become one of the most popular fields of study at American universities

4. Among the reasons given in the passage for the decline in the numbers of engineering students is that

A. the American schools still follow out - dated curricula curricula

B. university entrance requirements are far too demanding

C. many of them fail to acquire an adequate knowledge of mathematics and science at high schools.

D. it is generally recognized as one of the most difficult of all the courses

5. According to the passage, all school programmes.....

A. should be designed to make students aware of the engineering practices and principles

B. ought to give priority to sciences

C. must encourage children to make creative designs

D. Seem to put the emphasis on the need to diversify learning

một hình chữ nhật có chu vi 54m. Nếu tăng chiều dài thêm 3m, giảm chiều rộng xuống 4m thì diện giảm đi còn là 36m². Tính chiều dài và chiều rộng của khu vườn lúc đầu. Mọi người giúp e lập bảng luôn nhe :))). E cảm ơn nhìu

Cho hỗn hợp gồm CuO và Fe3O4 tác dụng với H2 ở nhiệt độ thích hợp hỏi nếu thu được 29,6g kim loại trong đó Fe nhiều hơn Cu là 4g thì cần bnhiêu lít khí H2 ?

Cho tam giác ABC trọng tâm G. Lấy các điểm M, N, P trên AG, BG, CG sao cho AG = 2MG, BG = 2NG, CG = 2PG. CM: tam giác MNP đồng dạng với tam giác ABC.