Read the following pasage and mark the letter A. B, C or D on your answer sheet to indicate the correct answer to each of the questions from 34 to 40.

As computers have become powerful tools for rapid and economic of production of picture, computer graphics has emerged as one of the most rapidly growing fields in computers scienee. It such used routinely in such diverse areas as business, industry, government, research, training, and madiecine.

One of of the initial uses of computer graphics and ultimately its greatest use, been as an aid to design, generally referred to as computer – aided degign (CAD). One of its greatest advantages is that designers can see how an object will lock after construction and make changes freely and much more quickly than with hands drafting. For three-dimensional rendering of machine parts, engineers rely heavily on CAD. Automobile, spacecraft, aerospace, and ship designers use CAD terluaiques to design vehicles and test their pertomance. Building designs are also created with computer graphics systems. Architect can design a building layout create a three-dimersional model, and even go for simulated “walk” through the rooms or around the outside of the building.

Business graphics is another rapidly growing are of computer graphics, where it is to create graphs, charts, and cost models summarize financial, statistical, msthematieal, scientific, and economic data. As an education aid, computer also has creative and commencial art applications, where it is used in advertissing, publishing and film productions, particulurly for computer animation, which is achieved by a sequential process.

What does the passage mainly discuss?

A. Routine uses of computers

B. Computer graphic applications

C. The rapidly grown ag field of camrater science

D. Computers as the architects af the future

cho em hỏi xíu : cứ 100g H2O hòa tan dc 50g NaCl mdd NaCl=150g ( làm sao để biết ạ

Cho 31,2 gam hỗn hợp Fe, Cu tác dụng với dung dịch HNO 3  đặc, nguội, dư thu được 17,92 lit khí màu nâu đỏ. Khối lượng Fe trong hỗn hợp là

A. 4,4 gam.

B. 1,2 gam.

C. 28,8 gam.

D. 5,6 gam.

1. Apples are not as expensive as oranges

2. he prefers playing golf to phaying tennis

3. because mai was a carelessness, she broke the cup

4. when did they begin building the guose

5. would you mind not smoking here

C + O₂ => CO₂

1 1 1

0,1

theo đề n_o2= V/22,4= 2,24/22,4= 0,1 mol

n_c=m/M = 2,4/12=0,2 mol

ta có n_{o2 ban đầu}/ n_{o2 pt <} n_{C ban đầu}/n_{C pt}

0,1/1 < 0,2/1

0,1<0,2

<=> C dư tính theo O₂

từ pt n_co2= 0,1 mol

=> V_o2= n.22,4=0,1.22,4=2,24l

Trong hình bên có ………………………..góc vuông

ta có V_{H2 = 985,6ml=0,9856l}

V_H2 sau phản ứng= 739,2ml=0,7392l

Trong phản ứng ta thấy cứ mỗi mol H2 tác dụng vs 1 mol O tạo thành H2o nên số mol O=H2

n_o=n_h2=V:22,4= 0,9856:22,4=0,044 mol

=> m₀=n.M=0,044.16=0,704g

m_R=2,552-0,704=1,848g

gọi a là hóa tri kim loại R

2R+2aHCl => 2RCl_a+aH2

2 2a 2 a

0,066:a 0,033

n_H2=V:22,4=0,7392:22,4=0,033

từ pt => n _R=0,066:a

mặt khác có m_R=1,848g

<=> 1,848=0,066:a.R

<=>28a=R

vì R là kim loại nên a nhân giá trị 1,2,3

ta nhân a=2 =>R=56

vậy R là Fe

gọi cthh của R là Fe_xO_y

ta có

n_Fe=x=m:M=1,848:56x=0,033 mol(1)

n_O=y=m:M=0,704:16y=0,044(2)

x:y=(1):(2)=0,033:0,044=3:4

vây cthh là Fe₃O₄

_{bạn xem kĩ nha}

theo đề: a-b=4 => a=b+4

ta có a³-12ab-b³= (b+4)³-12b(b+4)-b³

=b³+3.b².4+3.4².b+4³ -12b²-48b-b³

= b³+12b²+48b+4³-12b²-48b-b³

=4³=64