Phổ khối lượng (MS) là phương pháp hiện đại để xác định phân tử khối của các hợp chất hữu cơ. Kết quả phân tích phổ khối lượng cho thấy phân tử khối của hợp chất hữu cơ X là 60. Chất X có thể là
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- Acetic acid ($CH_3COOH$): $12 + 3 + 12 + 16 + 16 + 1 = 60$
- Methyl acetate ($CH_3COOCH_3$): $12 + 3 + 12 + 16 + 16 + 12 + 3 = 74$
- Acetone ($CH_3COCH_3$): $12 + 3 + 12 + 16 + 12 + 3 = 58$
- Ethanol ($C_2H_5OH$): $2(12) + 5(1) + 16 + 1 = 46$
Câu hỏi liên quan
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 from 36 to 40.
Parents of a Tokyo elementary school are up in arms at being asked to pay 730 dollars for their child's school uniform. A public elementary school in Tokyo's upmarket Ginza district has decided to adopt new school uniforms designed by the luxury Italian designer Armani. The bespoke uniforms, which include a hat and bag, are priced at over 80,000 (730 dollars) each. Parents are angry at the school's decision and are protesting at what they view as the exorbitant price for a uniform of an eight-year-old child. The school said it wanted a designer uniform that represented the rich area of Ginza. School officials visited top department stores and decided to ask the fashion brand Armani to design the uniform.
The expensive uniform has created such a fuss that it has been discussed in Japan's parliament. One lawmaker said that since the school is public and not private, "a certain price range needs to be considered". Finance Minister Taro Aso said. "Clearly it's expensive. It would be tough if a student could not afford to pay for it." Japan's education minister said steps would be taken to ensure the financial burden placed on parents for uniforms, "would not be excessive". Twitter users said young children are not interested in designer clothes. The school principal said. "With humility, I take the criticism that the explanation has been insufficient and not well-timed. I will go on explaining carefully to those concerned."
Who said the price of the uniform was clearly expensive?
Mark the letter A, B, C, or D on your answer sheet to indicate the word(s) OPPOSITE in meaning to the underlined word(s) in each of the following questions.
In sport commentaries, justice and impartiality to both sides are vital, but spontaneity and enthusiasm are valued by those watching or listening.
Hai phương pháp cơ bản trong nghiên cứu lịch sử 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.
Tips for Better Time Management
Want to get more done in less time? Follow these strategies for improving your productivity and focus!
Common Struggles:
Many people ___(7)___ effective time management, leading to stress and unfinished tasks. Research shows that nearly 70% of workers feel overwhelmed by their workload.
Actionable Solutions!
● Prioritize your tasks! Start by making a to-do list and ___(8)___ the most important tasks first.
● Break down big projects! Tackling a large project can be daunting, but breaking it into smaller, manageable parts helps ___(9)___ progress without feeling overwhelmed.
● Avoid distractions! ___(10)___ multitasking, focus on one task at a time to ___(11)___ your efficiency.
● Take breaks! Give yourself regular breaks to rest and recharge, which can help maintain a higher ___(12)___ of productivity.
- Một xí nghiệp mỗi ngày sản xuất ra
sản phẩm trong đó có
sản phẩm lỗi. Lần lượt lấy ra ngẫu nhiên hai sản phẩm không hoàn lại để kiểm tra. Tính xác suất của biến cố: Sản phẩm lấy ra lần thứ hai bị lỗi (làm tròn kết quả đến hàng phần trăm).
Read the following leaflet and mark the letter A, B, C, or D to indicate the option that best fits each of the numbered blanks from 7 to 12.
PROMOTE MENTAL WELL-BEING AT HOME!
Nurturing Your Mind and Spirit
Taking care of our mental health is just as important as our physical health, which helps us (7) ______ stress, build resilience, and lead fulfilling lives.
Facts and Figures
· Nature’s Impact: Studies show that spending time outdoors can significantly reduce stress (8) ______. However, many people feel they lack access to green spaces.
· Screen Time Concerns: Excessive daily screen time is linked to increased anxiety and depression. (9) ______ spending too much time on the phone screen, why don’t we go outside and get some fresh air?
Positive Actions You Can Take
· Designate a cozy corner in your home for reading, meditation, or simply unwinding. Make it inviting with soft lighting, plants, and comfortable seating.
· Start a gratitude journal! Write down three things you’re thankful for each day to cultivate a positive mindset.
· Make time for meaningful (10) ______ with family and friends. Connect with (11) ______ regularly help (12) ______ your support network and combats feelings of isolation.
· (9) ______ spending too much time on the phone screen, why don’t we go outside and get some fresh air?
Phương trình nào sau đây là phương trình mặt cầu?
- Trong tủ điện động lực của mạng điện sản xuất quy mô nhỏ, để bảo vệ mạng điện khi xảy ra quá tải, ngắn mạch thường sử dụng thiết bị bảo vệ là
Nguyên tử của nguyên tố magnesium (Mg) có 12 proton và 12 neutron. Nguyên tử khối của Mg là
Cho 20 g chất rắn ở nhiệt độ vào 100 g chất lỏng ở Cân bằng nhiệt đạt được ơ Nhiệt dung riêng của chất rắn
Read the following passage 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.
There are a wide variety of chatbots (18) ______, but chatbot52 is certainly one of the most impressive. Many readers have suggested that we try this chatbot, and it’s easy to see
why: it offers a great all-round user experience.
Perhaps the best feature of chatbot52 is (19) ______. This means that users can configure the chatbot quickly and begin working with it right away. Additionally, chatbot52’s AI adapts well to most situations, (20) ______. It is also very adaptable as it is used on instant messaging and social media platforms.
Chatbot52 has two major drawbacks. One is that it has limited answer options. This means that (21) ______. Also, some users have complained that chatbot52’s messages are too impersonal. Therefore, chatbot52 might not be the best option for complex questions that require personalized attention.
Overall, chatbot52 is an excellent choice due to its speed and accuracy. (22) ______, this AI-powered chatbot is a reliable option that is highly recommended.
Đối với xã hội hiện nay, môn Địa lí có vai trò nào sau đây?
“Ao thu lạnh lẽo nước trong veo,
Một chiếc thuyền câu bé tẻo teo.
Sóng biếc theo làn hơi gợn tí,
Lá vàng trước gió khẽ đưa vèo.”
(Nguyễn Khuyến, Câu cá mùa thu)
Nghệ thuật tiêu biểu nhất trong đoạn trích trên là
Công nghệ nano được ứng dụng rộng rãi trong lĩnh vực nào sau đây?
Triển vọng của ngành chăn nuôi là
- Nếu tại một thời điểm, giá trị ADC đọc được trên chân A0 của Arduino UNO là 1023 thì điện áp đặt tới A0 là
- Gọi L là độ tự cảm của cuộn dây, f là tần số dòng điện, ω là tần số góc của dòng điện và XL là cảm kháng của cuộn dây. Khi có điện áp đặt vào hai đầu cuộn cảm thì cảm kháng của cuộn dây được tính bằng công thức:
Read the following passage about The Elderly in Multicultural Societies: Challenges and Opportunities 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 multicultural societies, elderly individuals face unique challenges and important opportunities. As communities diversify rapidly, traditional support systems are constantly evolving. Seniors often navigate unfamiliar cultural environments while facing significant language barriers that lead to social isolation. These persistent obstacles frequently prevent full access to essential healthcare services or meaningful community participation. Fortunately, innovative local organizations address these critical issues by offering comprehensive translation services and culturally sensitive care options.
Technology presents both remarkable benefits and considerable difficulties for elderly individuals from various cultural backgrounds. Digital tools effectively connect seniors with distant family members globally, yet many older adults struggle substantially with these new communication methods. Recent research shows approximately 65% of elderly immigrants experience digital exclusion compared to native-born seniors. In response, numerous community centers have successfully established specialized technology workshops for older adults from diverse backgrounds, helping them maintain vital connections with overseas relatives and friends.
Cultural differences significantly impact elderly care approaches across communities. In collectivist cultures, elderly family members traditionally live with their children, while Western societies typically emphasize personal independence. This fundamental divergence creates tension when immigrant families attempt to adapt to new societal norms. However, vibrant multicultural environments provide valuable opportunities for exchanging diverse perspectives on aging. Many communities benefit tremendously from adopting hybrid approaches blending traditional cultural practices with modern care techniques, creating more comprehensive support systems.
Economic aspects of aging in multicultural contexts matter significantly for overall wellbeing. Elderly immigrants frequently face severe financial hardships due to limited retirement savings and persistent employment discrimination throughout their lives. Some progressive governments implement supportive policies addressing these vulnerable individuals' unique needs. Certain forward-thinking regions offer specialized employment programs for seniors with diverse cultural backgrounds, recognizing their valuable skills and extensive life experiences. Additionally, creative intergenerational initiatives connecting elderly immigrants with younger community members effectively foster mutual understanding and practical support, successfully transforming demographic challenges into meaningful community enrichment opportunities.
Which of the following is TRUE according to the passage?
Một người bơi ngang từ bờ bên này sang bờ bên kia của một dòng sông rộng 50 m có dòng chảy hướng từ Bắc đến Nam. Do nước sông chảy mạnh nên khi sang đên bờ bên kia thì người đó đã trôi xuôi theo dòng nước 50 m. Xác định độ lớn độ dịch chuyển của người đó.
Ý kiến nào sau đây là sai khi bàn về vấn đề cạnh tranh không lành mạnh?