Tiến hành thí nghiệm theo các bước sau:

Bước 1: Lấy vào ống nghiệm thứ nhất 0,5 ml dung dịch HNO₃ đặc (68%) và ống nghiệm thứ hai 0,5 ml  dung dịch HNO₃ 15%.

Bước 2: Cho vào mỗi ống nghiệm một mảnh nhỏ đồng kim loại. Nút các ống nghiệm bằng bông tẩm dung  dịch NaOH. Đun nhẹ ống nghiệm thứ hai.

Cho các phát biểu sau:

(a) Ở hai ống nghiệm, mảnh đồng tan dần, dung dịch chuyển sang màu xanh.

(b) Ở ống nghiệm thứ nhất, có khí màu nâu đỏ thoát ra khỏi dung dịch.

(c) Bông tẩm dung dịch NaOH có tác dụng hạn chế khí độc NO₂ thoát ra khỏi ống nghiệm.

(d) Có thể thay bông tẩm dung dịch NaOH bằng bông tẩm dung dịch NaCl.

Số phát biểu đúng là:

Cho hình chóp \(S. A B C\) có đáy \(A B C\) là tam giác đều cạnh \(a\) và \(S A=S B=S C=b(a>b \sqrt{2})\). Gọi \(G\) là trọng tâm \(\triangle A B C\). Xét mặt phẳng \((P)\) đi qua \(B\) vuông góc với \(S C\) tại điểm \(I\) nằm giữa \(S\) và \(C\). Diện tích thiết diện của hình chóp khi cắt bởi mặt phẳng \((P)\) là

Cho tứ diện ABCD. Gọi I, J là trọng tâm tam giác ABC, ABD. Tìm khẳng định đúng: 

Đâu là biện pháp xử lí chất thải trong chăn nuôi?

Read the passage and mark the letter A, B, C or D to answer the following questions.
Volunteering offers many of the same social benefits, with the added bonus of helping others and developing useful skills to put on your CV. Plus, students are in a unique position to help, suggests Tom Fox. "They can take their enthusiasm and excitement for opportunities and share their passions, subject knowledge and experience with people." The idea of giving up time for nothing might seem impractical at first, especially once the pressures of study and coursework or exams begin to mount up. However, Michelle Wright, CEO of charity support organization Cause4, suggests seeing volunteering as a two-way street. "I think it is fine for undergraduates to approach volunteering as a symbiotic relationship where doing good is just one part of the motivation for reaching personal and professional goals."
Katerina Rudiger, head of skills and policy campaigns at the Chartered Institute of Personnel and Development (CIPD), says: "Volunteering can be a valuable way of gaining that experience, as well as building confidence, broadening your horizons, becoming a better team player and developing those all- important 'employability skills' such as communication and decision making." Amanda Haig, graduate HR manager, agrees that volunteering can help your employment prospects. "Volunteering can demonstrate positive personality traits and skill sets, such as proactivity, and teamwork," she says.
A positive side-effect of volunteering is improving your time at university by getting involved in the local community. Leaving the student bubble can make your time as an undergraduate much more varied. At Bath Spa University, more than 1,000 students volunteered over the past year, doing everything from working on local environmental projects to helping in schools or assisting the elderly. ”Quite often there can be a divide between students and permanent residents," says students' union president Amy Dawson, "but if students invest a little time now, they will be giving something back to the local community and will reap the benefits in the future."
“You might also find that volunteering helps your studies if you choose the right program. At Lancaster, volunteering is linked into academic modules in some cases", explains Fox. "This has multiple wins. Students get to apply their learning in the classroom and share their interests with children in local schools or community organizations, while schools gain skilled students with a passion for a subject that enthuses their pupils."

What does the word "they" refer to in paragraph 3?

Điểm chung giữa các phân tử sinh học là

Pháp luật có vai trò như thế nào để Nhà nước phát huy quyền lực, sức mạnh trong quản lý nhà nước nhằm đảm bảo dân chủ, công bằng, bình đẳng và tiến bộ xã hội?

Trong mặt phẳng toạ độ \(Oxy\), cho hai điểm \(A( - 1; - 3)\) và \(B(3; - 2)\). Khoảng cách giữa hai điểm \(A\) và \(B\) bằng?

Ý nào sau đây không thuộc nội dung vai trò của sản xuất kinh doanh?

Tổ chức và hoạt động của 1 tổ chức tín dụng thuộc phạm vi áp dụng luật nào của nước ta?

Choose A, B, C or D that has the CLOSEST meaning to the given sentence in the question.

By the time they figured out the directions, they had already missed the conference.

Read the following passage about Life in The Future 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.

In the near future, technology is expected to bring about significant changes to how we lead our lives. One of the most notable shifts will be the way we keep up with the rapid pace of technological advancements. With smart homes and autonomous vehicles, our daily routines will increasingly depend on sophisticated systems designed to make our lives easier. For example, smart assistants will look out for our needs, such as ordering groceries, adjusting room temperatures, or even scheduling doctor’s appointments.

Another major development will be in communication. Today, we already use video calls to stay in touch with friends and family across the globe, but the future promises even more immersive experiences. Virtual reality could allow us to hang out with people in virtual spaces, regardless of where they physically are. As a result, geographical barriers will become less relevant, creating a more connected and global society.

Healthcare is also likely to transform. Advances in artificial intelligence will enable doctors to look after patients more efficiently, diagnosing diseases earlier and prescribing personalized treatments. These changes may extend our lifespan and improve our quality of life. Additionally, breakthroughs in renewable energy will play a key role in sustaining our future. With green energy sources, such as solar and wind power, we can cut down on harmful emissions and move toward a more sustainable planet.

While these advancements sound exciting, they also bring challenges. As technology becomes more integrated into our lives, we must be careful to ensure privacy and security. We need to watch out for potential risks, like data breaches and the misuse of personal information. With thoughtful planning, however, the future holds great promise for improving the way we live, work, and interact with the world.

Which of the following best paraphrases the underlined sentence in paragraph 4?

Choose A, B, C or D: No one enjoys ______ in public.

Một hệ quả quan trọng của cuộc cách mạng khoa học - công nghệ là

Biển báo dưới đây có ý nghĩa gì?

Mark the letter A, B, C, or D on your answer sheet to indicate the best arrangement of utterances or sentences to make a meaningful exchange or text in each of the following questions from 13 to 17.

a. Tom: Where did you fly to?

b. Lydia: No, we went to Portugal. And we went in August.

c. Tom: Did you go to Spain in July?

d. Lydia: We drove there, actually.

Cho tập hợp $A = \{ x + 1\, \big| \,x \in \mathbb{N}$, $x \le 5\}$. Tập hợp $A$ là

Đoạn trích phản ánh và ca ngợi điều gì?

Thuyết kiến tạo mảng được xây dựng trên cơ sở tiếp nối thuyết nào?