Nitrogen là nguyên tố dinh dưỡng quan trọng cho sinh vật, tuy nhiên hàm lượng nitrogen cao

có thể gây ô nhiễm nước. Một nghiên cứu xác định hàm lượng ion ammonium (NH\(_4^+\)) trong nước bề mặt ở Đồng bằng Sông Cửu Long và so sánh với tiêu chuẩn (hàm lượng NH\(_4^+\) < 3 mg L\(^{-1}\)) theo nguyên tắc sau:

- Chuẩn bị mẫu thử bằng cách pha loãng mẫu nước 10 lần.

- Ion NH\(_4^+\) được chuyển thành indophenol qua các phản ứng:

Cường độ màu (đậm nhạt) của dung dịch A tỉ lệ thuận với lượng indophenol trong dung dịch.

Khi đó máy đo cường độ màu có thể tính toán được hàm lượng indophenol, từ đó tính được hàm lượng NH+4 trong mẫu đo. Kết quả cho thấy hàm lượng ion NH\(_4^+\) trong mẫu thử là 1,44 mg L\(^{-1}\).

Các phản ứng cần thực hiện ở điều kiện pH trong khoảng từ 4 đến 13. Thiết bị chỉ đo được mẫu nước có hàm lượng NH\(_4^+\) nằm trong khoảng từ 0,26 đến 10,30 mg L\(^{-1}\).

(Tham khảo G.-J. Wilbers, M. Becker, L. T. Nga, Z. Sebesvári, and F. G. Renaud, "Spatial and temporal variability of surface water pollution in the Mekong Delta, Vietnam," Science of the Total Environment, vol. 485-486, pp. 653-665, Jul. 2014, doi: 10.1016/j.scitotenv.2014.03.049)

Trước khi tiến hành đo cường độ màu, để kiểm tra pH người ta nhúng giấy quỳ tím vào mẫu thứ, nhận thấy quỳ tím không đổi màu. Kết luận nào sau đây là đúng?

Read the following passage about the Reimagining International Cooperation 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.

Global environmental governance is changing how countries work together. Nations now understand that pollution, climate change, and resource problems cross borders. Traditional agreements between countries are not enough anymore. New approaches include businesses, local communities, and citizen groups working with governments. This all-hands-on-deck approach helps create better solutions for our planet. Many successful projects show that when different groups cooperate, they can solve difficult environmental problems that single countries cannot fix alone.

Environmental governance faces many challenges today. [I] Political differences between nations often slow down important decisions. [II] Some countries worry that strict environmental rules might hurt their economic growth. Despite these obstacles, new technologies are helping countries monitor environmental changes better. [III] Satellite data and computer models allow scientists to track forest loss, ocean pollution, and climate patterns. [IV] This information helps leaders make smarter decisions about protecting natural resources.

The future of environmental governance depends on innovation. Digital platforms now connect environmental experts around the world instantly. Young people are bringing fresh ideas through social media campaigns and protest movements. Indigenous communities contribute valuable traditional knowledge about sustainable living practices. Financial institutions are creating new ways to fund green projects in developing countries. These combined efforts are creating a more flexible and responsive system of global cooperation that can adapt to changing environmental conditions more quickly than old-fashioned diplomatic channels.

Effective environmental governance requires balance between global standards and local solutions. While international agreements provide important frameworks, communities need freedom to implement approaches that fit their unique situations. Successful governance models respect cultural differences while maintaining scientific standards. Education plays a crucial role in building public support for environmental policies. When citizens understand environmental issues, they make better choices and hold their leaders accountable. The most promising path forward combines strong international institutions with energetic local action to create lasting environmental solutions.

Which of the following is TRUE according to the passage?

Một loại nguyên tử hydrogen có cấu tạo đơn giản nhất, chỉ tạo nên từ 1 electron và 1 proton. Những phát biểu nào sau đây là đúng khi nói về nguyên tử hydrogen?

Read the following passage about endangered languages and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questionsfrom 31 to 40.

[I] Social media has become a dominant force in modern communication, offering a range of benefits and challenges. [II] It has revolutionized the way people interact, share information, and even form relationships. [III] While these platforms offer opportunities for connection and expression, they also have their drawbacks. [IV] For instance, excessive use of social media has been linked to a range of negative effects, including mental health issues, social isolation, and decreased productivity. [V] However, when used responsibly, social media can also offer a variety of positive outcomes, such as the ability to stay connected with loved ones, network professionally, and access valuable information and resources.

One of the major benefits of social media is its ability to keep people connected. For example, individuals who live far apart can maintain close relationships through regular communication on these platforms. Social media also facilitates professional networking, allowing users to connect with potential employers or clients, and enabling companies to promote their products and services to a global audience. Additionally, platforms like Facebook, Twitter, and Instagram provide a space for people to share ideas, opinions, and creative work, fostering a sense of community and collaboration.

Despite these advantages, there are serious concerns about the negative impact of social media, particularly on mental health. Studies have shown that excessive social media use can contribute to feelings of anxiety, depression, and loneliness. This is often attributed to the unrealistic portrayals of life that are commonly shared on these platforms, leading to comparisons that can make individuals feel inadequate or left out. Furthermore, constant exposure to negative news or online bullying can exacerbate these feelings and contribute to long-term psychological stress.

Another issue with social media is its potential to distract people from their daily responsibilities. With notifications constantly popping up and endless streams of content to scroll through, individuals may find it difficult to focus on tasks such as work, school, or personal obligations. This can result in decreased productivity and a lack of attention to important matters.

Ultimately, the impact of social media depends on how it is used. If individuals are mindful of their usage patterns and take steps to limit their time on these platforms, they can enjoy the benefits of staying connected and informed without the negative consequences. Parents, educators, and mental health professionals can also play a role in helping young people develop healthy habits and manage their social media use effectively.

Which of the following best summarizes the passage?

Anh B, anh X, anh Y và anh C cùng là bảo vệ tại một nông trường cao su. Một lần, phát hiện anh Y lấy trộm mủ cao su của nông trường đem bán, anh C đã giam anh Y tại nhà kho với mục đích tống tiền và nhờ anh X canh giữ. Ngày hôm sau, anh B đi ngang qua nhà kho, vô tình nhìn thấy anh Y bị giam, trong khi anh X đang ngủ. Anh B định bỏ đi vì sợ liên lụy nhưng anh Y đã đề nghị anh B tìm cách giải cứu mình và hứa sẽ không báo cáo cấp trên việc anh B tổ chức đánh bạc nên anh B đã giải thoát cho anh Y. Những ai sau đây vi phạm quyền bất khả xâm phạm về thân thể của công dân?

Đâu là các dấu hiệu đặc trưng của trao đổi chất và chuyển hóa năng lượng?

Read the following passage about Edible Landscapes for Community Resilience 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 18 to 22.

Urban food forests are becoming popular in many cities around the world. These special gardens (18)_________. Food forests which contain fruit trees, berry bushes, and edible plants help people learn about growing food and nature. These community gardens provide fresh food; (19)_________. The food is free for everyone to harvest; this system builds community connections and food security. Many cities now support these projects, recognizing their benefits and (20)_________. Unlike traditional parks, food forests need less water and maintenance. They grow many different plants together, which helps protect against pests and diseases naturally. Children love visiting these spaces to pick berries and learn about where food comes from.

Climate change makes growing local food more important than ever. When communities grow food together, (21)_________. Food forests can help reduce the urban heat island effect by providing shade and cooling the air. They also support important pollinators like bees and butterflies that help all plants grow better. Some food forests include community kitchens (22)_________. These spaces become centers for education about healthy eating and traditional cooking methods. Elderly community members often share their knowledge of plants and recipes with younger generations. This creates valuable connections between different age groups and cultures.

Nguyên tố nào có vai trò đặc biệt quan trọng đối với sự sống?

Hình ảnh dưới đây là hoạt động học sinh khối 11 tham quan thực tế tại nhà máy sản xuất phân bón.

Hoạt động trên tương ứng với phương pháp học tập hóa học nào?

Để lấy ra danh sách dữ liệu thỏa mãn một yêu cầu nào đó ta thực hiện?

Những phát biểu nào sau đây là đúng khi nói về mô hình Rutherford - Bohr?

Cơ chế thị trường có những ưu điểm gì?

Read the following passage about food addiction 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.

Few people would disagree that one of the world's most popular dishes is pizza. Twenty-two-year-old Zack certainly wouldn't. He would eat a variety of pizza-based items, including homemade pizza, precooked microwave pizza, and even pizza leftovers from the night before. He was consuming 800kg of pizza a year. As a child, Zack had eaten a wide variety of food. But he became addicted to pizza when he started secondary school. American school meals have often been criticised for the large amount of fast food present on the menu, and pizza is the star dish. Zack even spent all his pocket money on slices of pizza.

Naturally, Zack's family worried about his high-calorie, low-vitamin diet. So did Zack. In an attempt to break his addiction, Zack agreed to appear on a TV programme called Freaky Eaters. Its aim was to encourage food addicts to beat their addictions with the help of a psychologist and nutritionist. It wasn't easy. He had to eat a fish dish, while his brother sat in front of him enjoying... a pizza! However, Zack met the challenge and has never eaten pizza again.

Seventeen-year-old Stacy Irvine's friends visit her and discover that she has been rewarded thousands of free toys from fast food restaurants as a regular customer. Stacy's mother often gave her two-year-old girl a portion of fried chicken in a McDonald's restaurant. [I] Since then, Stacy has refused to eat anything else except for pieces of fried chicken, and as a result, her diet has created serious health. She has been warned that if she doesn't change her diet, she will die. [II] Stacy once collapsed due to lack of vitamins and nutrients and needed to be hospitalised. [III] She insisted that Stacy adopt a healthier lifestyle. However, worryingly, Stacy's mother said that while Stacy was beginning to understand the seriousness of her situation, she couldn't eat anything else but chicken nuggets. [IV]

Twenty-year-old Hanna Little was keen on chips. The only thing that Hanna consumed for fifteen years was one plate of chips after another. Not surprisingly, a diet that contained few nutrients and an excess of fat and carbohydrates could only have negative consequences. And it did because not only did Hanna develop health problems, but she also had to leave her job after collapsing at work. At five, Hanna became addicted to chips and refused to eat fruits and vegetables despite her mother's efforts. Hanna says that she was terrified of tasting the flavour of different types of food and she would feel anxious just at the idea of doing it. Parties, picnics and barbecues with friends and family used to be a nightmare. Furthermore, Hanna was soon seen as 'odd' by her friends' parents.

It wasn't until the age of sixteen that Hanna realised she had Selective Eating Disorder (SED). Despite this new knowledge, no solution was found. It wasn't until she lost her job before she started eating normally. Hanna sought therapy from psychologist Felix Economakis, who used hypnosis, a treatment that none of the doctors that she had seen before had mentioned, to get her to eat fruit after one one-hour session, and since then she has been willing to eat anything.... including chips!

(Adapted from Friends Global)

The phrase addicted to in paragraph 1 could be best replaced by _____.

Cuộc cách mạng công nghiệp lần thứ tư còn có tên khác là gì?

Enzyme có vai trò làm cho năng lượng hoạt hoá của các chất tham gia phản ứng như thế nào?

Một tên lửa khối lượng vỏ 200kg, khối lượng nhiên liệu 100kg, bay thẳng đứng lên nhờ nhiên liệu cháy phụt toàn bộ tức thời ra sau với vận tốc 400m/s. Tìm độ cao mà tên lửa đạt tới, biết sức cản của không khí làm giảm độ cao của tên lửa 5 lần. Lấy đơn vị là mét.

Trong không gian với hệ tọa độ Oxyz, cho điểm \(A(3; 1;-2)\), đường thẳng \(d: \frac{x-2}{2}=\frac{y+1}{1}=\frac{z-1}{-1}\) và mặt phẳng \((P): 2 x-y+3 z-5=0\).

Đường thẳng đi qua \(A\) và vuông góc với mặt phẳng \((P)\) là:

CHỦ ĐỀ: NGƯỜI Ở BẾN SÔNG CHÂU

(Tham khảo bài văn của chủ đề trong đường link dưới đây ở trang 21)

https://tvsthpt.dlib.vn/app/doc-sach-ebook/d02db18272fe

Và trả lời câu hỏi sau:

Từ thông tin của bài đọc, hãy hoàn thành câu sau bằng cách kéo thả các từ vào đúng vị trí.

- Tâm trạng của dì Mây khi được trở về quê hương, gặp lại bố ở bến sông: (...a...)

- Tâm trạng của dì Mây khi nói chuyện với chú San: (...b...)

- Tâm trạng của dì Mây sau khi đỡ đẻ cho cô Thanh: (...c...)

Lãnh thổ Nhật Bản trải ra theo một vòng cung dài khoảng bao nhiêu km?

Những phát biểu nào sau đây là đúng?

Bản chất của phong trào hội kín ở Nam Kì là gì?