Trong môi trường kiềm xảy ra sự chuyển hoá fructose thành glucose theo cân bằng:

${\text{HOCH}}_2{\left[\text{CH}\right(\text{OH}\left)\right]}_3{\text{COCH}}_2\text{OH}\stackrel{{\text{OH}}^{-}}{\rightleftharpoons }{\text{HOCH}}_2{\left[\text{CH}\right(\text{OH}\left)\right]}_4\text{CHO}$

 

Do đó, fructose vẫn tham gia phản ứng tráng bạc, mặc dù phân tử không có nhóm chức aldehyde.

Phát biểu nào sau đây là đúng?

Read the following passage about Huawei company and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 23 to 30.

Huawei is a multinational company that makes  telecommunications  parts for  mobile phones , network equipment  and other high-tech  devices . It is the second largest such company in the world. Huawei has its headquarters  in Shenzhen, which became China’s first special economic zone  in 1979.

The Chinese technology company, which was founded  about 20 years ago, has over 100,000 workers in all parts of the world, more than Microsoft.  Most of the company is owned by its  employees .  Huawei started out in the rural  areas in China. In those days most of the telecom contracts  went to  state-owned  Chinese or  foreign  firms. As the company grew, it took hold of urban markets in big Chinese cities and in 1997 it  expanded to other countries.

Today, Huawei is the second biggest manufacturer of telecom equipment, after Ericsson. In 2011,  annual  sales  is expected to be about $12 billion dollars and  likely to get three times as high within the next ten years. Working for Huawei is something many young Chinese engineers and IT workers dream of. The 1.5 square km site  has modern apartments that can be rented, its own hospital, restaurants and bars where employees  can go to in their free time. For Chinese standards workers are well-paid. Although   Huawei has been concentrating  on making telecom parts and whole networks, the company is also looking into other industries in an  attempt to diversify and grow. At Shenzhen  engineers  are experimenting on new forms of video conferencing, a branch  that is expanding rapidly . The Chinese hi-tech giant  is also starting to produce cloud-based  hardware and computers that work  out of the box . 

Even though Huawei is one of the world leaders in producing mobile phone parts it is also pushing into the consumer market with its own  brand  of computers, tablets and smartphones. So far Huawei has failed  to reach  the American market because of security  reasons. The American  government  thinks it has connections  with the Chinese  military and is afraid it will spy  on the American  public 

The word “diversify” in paragraph 3 could be best replaced by ________.  

Đồ thị biểu diễn mối quan hệ giữa gia tốc và li độ của vật dao động điều hòa là

Read the following leaflet and mark the letter A, B, C or D on your answer sheet to indicate the option that bestfits each of the numbered blanks from 7 to 12.

Social Media: A Double-Edged Sword

Social media has become an (7) _____  part of modern life. While it connects people worldwide, it also poses challenges we must address.

Benefits:

Social media enables us to share knowledge, connect with friends, and promote businesses. Many people use it to explore (8) _____ exciting opportunities, from freelancing to e-learning.

Challenges:

However, overuse of social media can lead to addiction. People often find it hard to (9) _____ from their screens, affecting their productivity and health. Furthermore, misinformation spreads quickly on platforms, (10) _____risks to individuals and society.

Recommendations:

To make the most of social media, users should focus on reliable content and limit their time online. Effective content moderation policies are needed to create safer digital spaces. (11) _____ spending hours scrolling aimlessly, set time limits to achieve a balanced routine.

By following these steps, we can enjoy numerous benefits while avoiding its pitfalls. Remember, responsible use is key in the (12) _____ of this digital era.

Khi cung nhỏ hơn cầu và giá cả tăng thì các chủ thể sản xuất thường có xu hướng gì?

Khoa học được chia làm mấy nhóm?

1 gram electron có bao nhiêu hạt?

Read the following passage about the Pathways from Today's Actions to Tomorrow's World and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.

As we stand at the crossroads of environmental decision-making, the actions we take today will shape our world in 2050. Scientists warn that we're skating on thin ice with current consumption patterns and carbon emissions. Global temperatures could rise by 2-4 degrees Celsius unless significant changes occur within the next decade. Many countries have pledged to achieve carbon neutrality by 2050, but these promises require immediate implementation. Individual choices in transportation, energy usage, and consumption can collectively influence whether future generations inherit a sustainable planet or face severe climate consequences.

[I] Technological innovation represents our greatest hope for addressing environmental challenges by 2050. [II] Renewable energy sources like solar and wind are becoming increasingly affordable, potentially replacing fossil fuels entirely within thirty years. [III] Electric vehicles may dominate transportation networks, while vertical farming could transform food production in urban areas. [IV] However, these technological solutions must be developed and deployed equitably to avoid creating new disparities between wealthy and developing nations.

Social structures will undergo dramatic transformation by 2050 as demographic shifts reshape communities worldwide. Aging populations in developed countries will necessitate new approaches to healthcare, retirement, and social support systems. Meanwhile, climate migration may force millions to relocate from vulnerable coastal and drought-prone regions. Education systems must evolve to prepare our students for jobs that don't yet exist, emphasizing their adaptability and lifelong learning. Cities will need to become more resilient, incorporating green spaces and sustainable infrastructure to support growing populations.

Economic models must fundamentally change by 2050 to balance prosperity with environmental responsibility. The traditional focus on continuous growth may shift toward measuring success through wellbeing indicators rather than GDP alone. Circular economy principles will likely replace linear production models, with products designed for reuse and recycling. Resource-sharing platforms may become more prevalent, reducing individual consumption while maintaining living standards. Companies implementing genuinely sustainable practices will thrive, while those clinging to environmentally harmful methods may disappear entirely. The transition presents both challenges and opportunities for businesses willing to embrace innovation and sustainability.

Which of the following is TRUE according to the passage?

Cấu hình electron của nguyên tử nguyên tố X là 1s²2s²2p⁶. Số hiệu nguyên tử của X là

Trong một nhà máy sản xuất ammonia theo quy trình Haber, giai đoạn sản xuất khí hydrogen băng phản ứng của methane và nước được thực hiện theo phương trình hóa học (1) như sau:

$\left(1\right) C{H}_4\left(g\right)+H_{2}O\stackrel{xt}{\to }CO\left(g\right)+3H_2 \left(g\right)$

Phản ứng (1) là phản ứng thu nhiệt mạnh. Lượng nhiệt nảy được cung câp từ quá trình đốt cháy hoản toàn khí methane theo phương trình hóa học (2):

$\left(2\right) C{H}_4\left(g\right)+2O_2\left(g\right)\to C{O}_2\left(g\right)+2H_{2}O\left(g\right)$

Xét các phản ứng ở điều kiện chuẩn và hiệu suất chuyển hóa của methane là 100%. Tính khối lượng khí methane (theo tấn, làm tròn đến hàng phần trăm) cần thiết để sản xuất 0,30 tấn H2(g) trong giai đoạn trên. Biết 90% lượng nhiệt tỏa ra từ phản ứng (2) được cung cấp cho phản ứng (1) và các giá trị nhiệt tạo thành ${∆}_f{H}_{298}^0$ của các chất ở điều kiện chuẩn được cho trong bảng sau:

Dãy nào sau đây gồm các đồng vị của cùng một nguyên tố hoá học?

Liên bang Nga có đường biên giới trên đất liền dài khoảng bao nhiêu?

Read the following passage about the Science in Service of Humanity and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.

Science has come out of its shell in laboratories to become a powerful force for human advancement. Modern scientific endeavors increasingly focus on addressing real-world challenges affecting communities globally. From developing vaccines that save millions to creating technologies connecting people across continents, science serves humanity in countless ways. This shift represents a fundamental evolution in how we perceive scientific progress—not merely academic pursuit but a practical tool for improving lives and solving pressing problems.

[I] Medical breakthroughs exemplify how science directly benefits humanity. [II] For instance, gene therapy offers hope for those with inherited conditions, while artificial intelligence helps diagnose diseases earlier and more accurately. [III] These advancements didn't happen overnight; scientists had to burn the midnight oil for years before achieving success. [IV] Their perseverance demonstrates that when science targets humanitarian goals, results can transform society profoundly.

Environmental science has emerged as another crucial domain where laboratory work translates into human welfare. Climate scientists provide data informing policy decisions affecting billions. Conservation biologists develop strategies to protect biodiversity, ensuring future generations benefit from natural resources. Agricultural researchers create drought-resistant crops helping communities withstand changing climate conditions. Despite these contributions, environmental science faces challenges including funding limitations, political resistance, and urgency of addressing accelerating climate change. Nevertheless, dedicated scientists continue their work, recognizing environmental health directly impacts human wellbeing.

The future of science in service of humanity looks increasingly collaborative and inclusive. Modern approaches incorporate diverse perspectives, including indigenous knowledge and community participation. Citizen science projects engage non-professionals in data collection, democratizing the scientific process. Open-access publishing makes research findings available to anyone with internet access, not just wealthy institutions. These developments suggest science's greatest potential lies in becoming more accessible and responsive to human needs. As we face complex global challenges, from pandemics to climate change, science serving humanity offers our best hope for a sustainable future.

Which of the following best summarises paragraph 3?

Đáp án nào sau đây không phải là nghệ thuật độc đáo được sử dụng trong bài Thu điếu?

Những nơi nào sau đây trong năm không có hiện tượng Mặt Trời lên thiên đỉnh?

Read the following advertisement and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 1 to 6.

"Welcome to FitLife Gym, the newest fitness center in town! We take pride in offering you a modern space equipped with state-of-the-art equipment and a team of expert trainers (1)______ to helping you achieve your fitness goals. At FitLife, we provide a variety of programs designed (2)______  all fitness levels, from beginners to advanced athletes.

Not only do we feature cardio and strength training areas, but we also offer yoga, pilates, and engaging group classes (3)______you motivated. With (4)______ you can easily choose the right plan that fits your schedule and lifestyle. At FitLife Gym, you'll experience the support of our dedicated team in a friendly and encouraging (5)______ . Join us today to kickstart your health journey and discover the difference that a supportive community can (6)______a difference in reaching your fitness aspirations!"

Hàm số \(y = {\log _a}x\left( {a > 0,a \ne 1} \right)\) đồng biến trên \(\left( {0; + \infty } \right)\) với giá trị nào của a dưới đây?