Đổi 250g = 0,25kg

Nhiệt lượng của nước là :

Q_nước = m.C ( t₁ - t₂ )
Q_nước= 2. 4200.(100-30 )

Q_nước=588000 ( J )

Nhiệt lượng của nhôm là :

Q_nhôm=m.C(t₁-t₂)

Q_nhôm=0,25.880(100-30)

Q_nhôm=15400 ( J )

Nhiệt lượng cần cung cấp là :

Q= Q_nước+Q_nhôm

Q= 588000 + 15400 =603400(J)

- Nồng độ Glucô trong máu luôn ổn định 12% ( 1,2g/lít)

- Khi nồng độ Glucô trong máu nhỏ hơn 12% thì sẽ kích thích tế bào anpha tiết ra hoocmôn Glucagôn để biến đổi Glucơzen -> Glucô được đưa vào máu .

- Khi nồng độ Glucô trong máu lớn hơn 12% thì tế bào bêta tiết ra hoocmôn Insulin để biến đổi Glucô -> Glucơzen được dự trữ ở gan và cơ .

- Nhờ tác động của TB anpha và beta mà nồng độ Glucô trong máu luôn ổn định

- Chúc bạn học tốt <3 ( Cái này là cô mình dạy trên trường nhé không copy mạng nè bạn cứ yên tâm mà chép ! : )) .

a) Đặt 2 số đấy là 2k+1 và 2k+3 và UWCLN của chúng là d . Ta có :

2k+1 chia hết cho d ; 2k+3 chia hết cho d => 2k+3 -(2k+1) chia hết cho d hay 2 chia hết cho d

d ko thể bằng 2 vì d là ước của 2 số lẻ => d=1 => 2 số lẻ liên tiếp nguyên tố cùng nhau .

b) Gọi ƯCLN của 2n+5 và 3n+7n là d . Ta có

2n+5 chia hết cho d => 6n+10 chia hết cho d

3n+7 chia hết cho d => 6n+ 14 chia hết cho  d

=> 6n+14 -(6n+10) chia hết cho d hay 4 chia hết cho d mà d ko thể bằng 2 hay 4 vì d là ước của 2n+5 ( số lẻ ) => d=1

=> 2n+5 và 3n+7 là 2 số nguyên tố cùng nhau .

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

Although they are an inexpensive supplier of vitamins, minerals, and high-quality protein, eggs also contain a high level of blood cholesterol, one of the major causes of heart diseases. One egg yolk, in fact, contains a little more than two-thirds of the suggested daily cholesterol limit. This knowledge has caused egg sales to plummet in recent years, which in turn has brought about the development of several alternatives to eating regular eggs. One alternative is to eat substitute eggs. These egg substitutes are not really eggs, but they look somewhat like eggs when they are cooked. They have the advantage of having low cholesterol rates, and they can be scrambled or used in baking. One disadvantage, however, is that they are not good for frying, poaching, or boiling. A second alternative to regular eggs is a new type of egg, sometimes called 'designer' eggs. These eggs are produced by hens that are fed low-fat diets consisting of ingredients such as canola oil, flax, and rice bran. In spite of their diets, however, these hens produce eggs that contain the same amount of cholesterol as regular eggs. Yet, the producers of these eggs claim that eating their eggs will not raise the blood cholesterol in humans.

Egg producers claim that their product has been portrayed unfairly. They cite scientific studies to back up their claim. And, in fact, studies on the relationship between eggs and human cholesterol levels have brought mixed results. It may be that it is not the type of egg that is the main determinant of cholesterol  but the person who is eating the eggs. Some people may be more sensitive to cholesterol derived from food than other people. In fact, there is evidence that certain dietary fats stimulate the body's production of blood cholesterol. Consequently, while it still makes sense to limit one's intake of eggs, even designer eggs, it seems that doing this without regulating dietary fat will probably not help reduce the blood cholesterol level.

What is the main purpose of the passage?

A. To introduce the idea that dietary fat increases the blood cholesterol level. 

B. To inform people about the relationship between eggs and cholesterol. 

C. To persuade people that eggs are unhealthy and should not be eaten 

D. To convince people to eat 'designer' eggs and egg substitutes.

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the question.

          Life expectancy is the period of time that a person can expect to live. Life expectancy varies greatly between genders and cultures. It used to be that women had a lower life expectancy than men (1 in every 4 women died in childbirth), but now they live an average of four to five years longer than men. Life expectancy has been increasing rapidly over the last centuries. With the advent of such modern miracles as sewers, medicine and a greater understanding of how diseases are spread, our life expectancy has increased by 25 – 30 years.

          In developing countries like Swaziland, where there is a high HIV/AIDS rate, life expectancy is as low as 32,6 years. In developed countries like Australia, life expectancy rates as high as 81 years. There are an increasing number of factors which can cancel out the disadvantages you have. The one that we are looking at now is how your career can affect your life expectancy. Choosing the wrong career can result in a shorter life!

          If you want your career to positively influence your life expectancy, you have to be made of money. That’s right. Rich people in wealthy areas of England and France live 10 years longer than the people in poorer areas. Having a successful career has its drawbacks, too if the result of hard work its stress.

          Stress can lead to a number of psychological disorders such as depression, anxiety, fatigue, tension and aggression. These conditions may result in a lack of concentration and an increase in serious injuries at work. They can also lead to high blood pressure and heart attacks which seriously affect life expectancy.

          If you are worried that your job might decrease your  life expectancy, you probably need to avoid careers on “dangerous jobs” list such as timber cutters, pilots, construction workers, roofer, truck drivers.

          So if you don’t want to kick the bucket at an early age, choose a career in something other than timber cutting, but above all, remember to relax.

From Pre-Essence Reading by Rachel Lee, Longman

It can be inferred from the paragraph 3 that the disadvantage of a successful career is that _______.

A. You won’t have to take a job on the “dangerous jobs” list 

B. You are at the greater risk of being a victim of crime 

C.  There is a high number of work – related injuries 

D.  You are more likely to be under stress.

Không giải phương trình, hãy xác định các hệ số a, b, c, tính biệt thức Δ và xác định số nghiệm của mỗi phương trình sau: 1 , 7 x 2 - 1 , 2 x - 2 , 1 = 0

Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions

Unfortunately, the company closed down because it couldn’t keep  ________ with rapidly changing technology

A. speed

B. fast

C. time

D. pace

Đốt cháy hoàn toàn 22,9 gam hỗn hợp X gồm hai este đơn chức, mạch hở tạo bởi cùng một ancol với hai axit cacboxylic kế tiếp nhau trong dãy đồng đẳng, thu được 1,1 mol CO₂ và 15,3 gam H₂O. Mặt khác, toàn bộ lượng X trên phản ứng hết với 300 ml dung dịch NaOH 1M thu được dung dịch Y. Cô cạn dung dịch Y thu được m gam chất rắn khan. Giá trị của m có thể là

A. 23,9

B. 18,4

C. 20,4.

D. 19,0