Trong mỗi phát biểu sau, em hãy chọn đúng hoặc sai.
a) Trong các phản ứng hạt nhân, điện tích và số khối được bảo toàn nên số neutron cũng được bảo toàn.
b) Cho phản ứng hạt nhân \(_0^1n + _{92}^{235}{\rm{U}} \to _{38}^{94}{\rm{Sr}} + {\rm{X}} + 2_0^1n.\) Hạt nhân X có 54 proton và 86 neutron.
c) Trong phản ứng nhiệt hạch: \(_1^2{\rm{H}} + _1^3{\rm{H}} \to _2^4{\rm{He}} + _0^1n + 17,6{\rm{MeV}}\), năng lượng cần cung cấp cho phản ứng là \(17,6{\rm{MeV}}.\)
d) Công nghệ hạt nhân đang được ứng dụng nhiều trong y học, công nghiệp, nông nghiệp, khảo cổ học, thực phẩm.
Trong mỗi phát biểu sau, em hãy chọn đúng hoặc sai.
a) Trong các phản ứng hạt nhân, điện tích và số khối được bảo toàn nên số neutron cũng được bảo toàn.
b) Cho phản ứng hạt nhân \(_0^1n + _{92}^{235}{\rm{U}} \to _{38}^{94}{\rm{Sr}} + {\rm{X}} + 2_0^1n.\) Hạt nhân X có 54 proton và 86 neutron.
c) Trong phản ứng nhiệt hạch: \(_1^2{\rm{H}} + _1^3{\rm{H}} \to _2^4{\rm{He}} + _0^1n + 17,6{\rm{MeV}}\), năng lượng cần cung cấp cho phản ứng là \(17,6{\rm{MeV}}.\)
d) Công nghệ hạt nhân đang được ứng dụng nhiều trong y học, công nghiệp, nông nghiệp, khảo cổ học, thực phẩm.
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b) Đúng. Ta có: $0 + 235 = 94 + A_X + 2*1 \Rightarrow A_X = 139$ và $1 + 92 = 38 + Z_X + 2*0 \Rightarrow Z_X = 55$. Vậy số neutron trong X là $A_X - Z_X = 139 - 55 = 84$. Đề bài nói 54 proton và 86 neutron, vậy phát biểu này sai.
c) Sai. Phản ứng tỏa năng lượng $17,6{\rm{MeV}}$ chứ không cần cung cấp.
d) Đúng. Công nghệ hạt nhân có nhiều ứng dụng thực tế.
Câu hỏi liên quan
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. David: Good idea! It's hot today and the tree gives nice shade.
b. Sarah: Do you want to sit under the tree and have our lunch?
c. Sarah: Great! I have sandwiches and apples in my bag. Let's eat!
d. David: Yes, it's beautiful. I think it's very old too.
e. Sarah: Look at that big tree! It has many green leaves.
Read the following leaflet 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 7 to 12.
STAY SAFE: UNDERSTANDING SCAMS AND HOW TO PREVENT THEM
What is a scam?
A scam is a deceptive scheme delivered through digital communications with the intent to steal money or personal information. These schemes take many forms, including online fraud, phishing emails, and fake lotteries. In (7) _____ words, scams are tricks that prey on your trust and can lead to significant financial loss.
Common types of scams
- Phishing: fraudulent emails or messages that appear to be from legitimate sources, tricking you into (8) _____ personal information.
- Lottery scams: notifications claiming you’ve won a (9) _____, requiring you to pay a fee to claim it.
- Other scams: these can include fake charities, advance-fee scams, and online auction fraud, each designed to exploit individuals in different ways.
Tips to prevent scams
- Verify sources: always check the (10) ____ of requestions for personal information.
- Root out suspicious communications: don’t engage with unknown contacts and report any suspicious emails or calls to the authorities (11) _____ potential scams.
- Protect your information: use strong passwords and enable two-factor authentication on your accounts to add an extra (12) ______ of security.
Read the following passage about news 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.
[I] Wildlife conservation refers to the efforts made to protect and preserve wild animal species and their habitats. [II] It is crucial for maintaining biodiversity, which plays a vital role in ecosystem stability and health (Smith & Jones, 2018). [III] Unfortunately, many species are threatened due to habitat destruction, poaching, and climate change, making conservation efforts more urgent than ever. [IV]
One of the primary reasons for wildlife conservation is the preservation of biodiversity. A diverse range of species contributes to ecosystem services, such as pollination, water purification, and climate regulation. The loss of a single species can disrupt these services and lead to ecological imbalances. For instance, the decline of pollinators like bees has serious implications for food production and agriculture (Global Biodiversity Outlook, 2020).
Moreover, wildlife conservation has significant economic benefits. Many communities depend on ecotourism, which relies on healthy wildlife populations and intact ecosystems. According to a study by the World Wildlife Fund (WWF), ecotourism can generate billions of dollars in revenue, providing jobs and supporting local economies (WWF, 2021). Protecting wildlife not only safeguards natural resources but also creates sustainable livelihoods for local populations.
However, effective wildlife conservation requires a collaborative approach. Governments, non-governmental organizations, and local communities must work together to implement policies and strategies that promote conservation efforts. Community-based conservation initiatives, where local people actively participate in protecting their natural resources, have shown promising results. These initiatives empower communities and ensure that conservation efforts are tailored to local needs and contexts (Bennett & Dearden, 2014).
Which of the following can be inferred from the passage?
Nghiệm của phương trình \(2^{2 x-1}=8\) là:
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 questions from 23 to 30.
UNEMPLOYMENT IN VIETNAM
Unemployment is a growing concern in Vietnam, particularly among young graduates. The rapid expansion of the labor market has not kept pace with the increasing number of students completing higher education. According to recent statistics, the youth unemployment rate is nearly 20%, which poses challenges for the economy and society. Many young people struggle to find jobs that match their skills and qualifications.
Additionally, the COVID-19 pandemic has exacerbated the situation, leading to layoffs and reduced hiring across various sectors. Industries such as tourism and hospitality have been hit hard, with many businesses closing or operating at limited capacity. This has resulted in a significant loss of jobs, especially for those in the informal sector.
To combat unemployment, the Vietnamese government is implementing various initiatives. These include vocational training programs aimed at equipping young people with practical skills that are in demand in the labor market. Furthermore, the government is encouraging entrepreneurship by providing financial support and resources for start-ups.
Technology is vital in tackling unemployment issues. Online job portals and social media platforms have become valuable tools for job seekers, allowing them to connect with potential employers more easily. Additionally, remote work opportunities have expanded, enabling individuals to access jobs beyond their local area.
Despite the challenges, there is hope for the future. As the economy recovers and diversifies, new job opportunities are expected to arise. Continuous investment in education and skill development will be key to reducing unemployment rates in the long term.
The word “exacerbated” in paragraph 2 is OPPOSITE in meaning to_________
- Chuyển dịch cơ cấu kinh tế theo hướng công nghiệp hoá, hiện đại hoá không nhằm mục tiêu nào sau đây?
Cho tập hợp E = {x ∈ ℕ | x là ước chung của 20 và 40}.
Tập hợp E có bao nhiêu phần tử?
- Gió mùa hạ thổi đến nước ta vào khoảng từ tháng 5 đến tháng 10 có nguồn gốc từ
Yếu tố nào sau đây thể hiện rõ rệt nhất sự khác biệt giữa mạng LAN và Internet trong bối cảnh sử dụng và quản lý dữ liệu?
Sơ đồ mạch điện trong hình bên thể hiện có
Choose A, B, C or D that has the OPPOSITE meaning to the underlined word/phrase in each question.
Many new tools have been developed to facilitate the accuracy and efficiency of scientific experiments.
Read the following passage about studying abroad 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.
Successful students often do the followings while studying. First, they have an overview before reading. Next, they look for important information and pay greater attention to it (which often needs jumping forward or backward to process information). They also relate important points to one another. Also, they activate and use their prior knowledge. When they realize that their understanding is not good, they do not wait to change strategies. Last, they can monitor understanding and take action to correct or “fix up” mistakes in comprehension.
Conversely, students with low academic achievement often demonstrate ineffective study skills. [I] They tend to assume a passive role in learning and rely on others (e.g., teachers, parents) to monitor their studying. [II] For example, low-achieving students often do not monitor their understanding of content; they may not be aware of the purpose of studying; and they show little evidence of looking back or employing “fix-up” strategies to fix understanding problems. [III] Students who struggle with learning new information seem to be unaware that they must extend effort beyond simply reading the content to understand and remember it. [IV]
Children with learning disabilities do not plan and judge the quality of their studying. Their studying may be disorganized. Students with learning problems face challenges with personal organization as well. They often have difficulty keeping track of materials and assignments, following directions, and completing work on time. Unlike good studiers who employ a variety of study skills in a flexible yet purposeful manner, low-achieving students use a restricted range of study skills. They cannot explain why good study strategies are important for learning; and they tend to use the same, often ineffective study approach for all learning tasks, ignoring task content, structure or difficulty.
Which of the following best summarizes the passage?
a. Anna: I can’t believe how much the story changed throughout the book. What did you think of the ending?
b. Mark: I just finished reading that fascinating novel last night, and it left me with so many thoughts.
c. Anna: I found the ending quite surprising, especially with that twist involving the main character.
Read of the following leaflet 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 7 to 12.
Join Our Community Gardening Program
Are you interested in growing your own vegetables? If you’ve tried our workshops, you’ll want to sign up for (7)_________session! In our program, participants (8)_______ to share tips and techniques for successful gardening. Each week, we focus on a different plant variety, providing you with the (9)_______you need for successful harvests.
Our experts will guide you (10)________ the art of sustainable gardening. You'll also receive a starter kit that includes seeds, soil, and tools, making it easier for you to begin your gardening (11)_______. We believe that a (12)_________ of the benefits of gardening include a sense of community and the joy of growing your own food.
Nhiệt độ nóng chảy của kim loại nhóm IA (kim loại kiềm) có xu hướng giảm từ lithium đến caesium. Nhiệt độ nóng chảy cùa một số kim loại kiềm được cho ở bảng sau:
Kim loại
Li
Na
Rb
Cs
Nhiệt độ nóng chảy (°C)
180
98
x
29
Giá trị của x phù hợp là
Lĩnh vực nào dưới đây nghiên cứu về cấu tạo và các hoạt động sống của tế bào?
Cho hàm số \(f(x)=x^{3}-3 x^{2}+(k-2) x+1\).
Để đồ thị hàm số \(f(x)\) cắt trục \(O x\) tại 3 điểm phân biệt có hoành độ lập thành cấp số cộng thì \(k\) thuộc khoảng nào dưới đây?
Địa lí giúp các em có được những hiểu biết cơ bản về
Nguyên tử magnesium có 3 đồng vị là (chiếm 78,6%), (chiếm 10,1%), (chiếm 11,3%). Nguyên tử khối trung bình của magnesium (Mg) là?
Quy luật phân ly có ý nghĩa thực tiễn là gì?