Một bức xạ truyền trong không khí với chu kì 8,25.10-18 s. Bức xạ này thuộc vùng bức xạ
Một bức xạ truyền trong không khí với chu kì 8,25.10-18 s. Bức xạ này thuộc vùng bức xạ
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Tần số của bức xạ là: $f = \frac{1}{T} = \frac{1}{8,25.10^{-18}} \approx 1,21.10^{17}$ Hz.
Vì tần số này lớn hơn tần số của tia tử ngoại (khoảng $10^{15}$ Hz đến $10^{17}$ Hz), bức xạ này thuộc vùng tử ngoại.
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Đọc đoạn trích sau và trả lời câu hỏi:
Thuở nhỏ tôi ra cống Na câu cá
níu váy bà đi chợ Bình Lâm
bắt chim sẻ ở vành tai tượng Phật
và đôi khi ăn trộm nhãn chùa Trần.
(Đò Lèn, Nguyễn Duy)
Xác định phương thức biểu đạt chính được sử dụng trong đoạn thơ trên.
Trong thí nghiệm chứng minh quá trình vận chuyển nước ở thân, có thể sử dụng hóa chất nào dưới đây?
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)
Which of the following best summarises the passage?
Chủ thể có vai trò tác động để điều chỉnh và khắc phục những vấn đề nảy sinh trong quá trình phát triển kinh tế - xã hội được gọi là gì?
Nhà mẹ Lê là một gia đình một người mẹ với mười một người con. Bác Lê là một người đàn bà quê chắc chắn và thấp bé, da mặt và chân tay nhăn nheo như một quả trám khô. Khi bác mới đến phố, ai ai cũng chú ý đến đám con của bác: mười một đứa, mà đứa lớn mới có mười bảy tuổi! Đứa bé nhất hãy còn bế trên tay.
Mẹ con bác ta ở một căn nhà lá. Chừng ấy người chen chúc trong một khoảng rộng độ bằng hai chiếc chiếu, có mỗi một chiếc giường nan gãy nát. Mùa rét thì trải ổ rơm đầy nhà, mẹ con cùng nằm ngủ trên đó, trông như một cái ổ chó, chó mẹ và chó con lúc nhúC. Đối với người nghèo như bác một chỗ ở như thế cũng tươm tất lắm rồi. Nhưng còn cách kiếm ăn? Bác Lê chật vật, khó khăn suốt ngày cũng không đủ nuôi từng ấy đứa con. Từ buổi sáng tinh sương, mùa nực cũng như mùa rét, bác ta đã phải trở dậy để đi làm mướn cho những người trong làng. Những ngày có người mướn ấy, tuy bác phải làm vất vả, nhưng chắc chắn buổi tối được mấy bát gạo và mấy đồng xu về nuôi lũ con đói đợi ở nhà.[...] Trong ngày hè nóng nực, con bác Lê đứa nào cũng lở đầu – bác ta bảo là một cái bệnh gia truyền từ đời ông tam đại – nên bác lấy phẩm xanh bôi cho chúng nó. Trông mẹ con bác lại giống mẹ con đàn gà, mà những con gà con người ta bôi xanh lên đầu cho khỏi lẫn. Người phố chợ vẫn thường nói đùa bác Lê về đàn con đông đúc ấy.
(Thạch Lam, Nhà mẹ Lê, In trong Gió lạnh đầu mùa - tập truyện ngắn, NXB Văn học, 2022)
Từ “gia truyền” được hiểu là gì?
Hai đường thẳng nằm trong cùng một mặt phẳng và không có điểm chung thì hai đường thẳng đó?
Cho 5 điểm M, N, P, Q, R. Tính tổng ?
Phương án nào sau đây thuộc ngành cơ khí?
Read the following passage about Healthy Benefits of Yoga 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.
Yoga is a healthy lifestyle. One of the benefits of yoga is that you can choose a yoga style that is suitable for your lifestyle, such as hot yoga, power yoga, relaxation yoga, etc. If you are a yoga beginner, Hatha Yoga, which focuses on basic postures at a comfortable pace, would be great for you. If you want to increase strength through using more of your own body’s resistance, Power Yoga may be right for you. Whether you prefer you're at home, in a private session, watching a DVD or at a studio or gym, there are a huge variety of options available to suit your goals and needs.
Improved flexibility is one of the first and most obvious benefits of yoga. During your first class, you probably won’t be able to touch your toes. But if you stick with it, you’ll notice a gradual loosening, and eventually, seemingly impossible poses will become possible. Each of the yoga poses is built to reinforce the muscles around the spine, the very center of your body, which is the core from which everything else operates.
When the core is working properly, posture is improved, thus alleviating back, shoulder, and neck pain. Strong muscles do more than look good. They also protect us from conditions like arthritis and back pain, and help prevent falls in elderly people. And when you build strength through yoga, you balance it with flexibility. If you just went to the gym and lifted weights, you might build strength at the expense of flexibility.
Yoga gets your blood flowing. More specifically, the relaxation exercises you learn in yoga can help your circulation, especially in your hands and feet. Yoga also gets more oxygen to your cells, which function better as a result. Twisting poses are thought to wring out venous blood from internal organs and allow oxygenated blood to flow in once the twist is released. Many studies found that a consistent yoga practice improved depression and led to greater levels of happiness and better immune function.
In which paragraph does the author describe the types of yoga suitable for different goals?
- Tính chất vật lí nào sau đây không phải là tính chất chung của kim loại?
Read the following passage about education in Nepal 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.
A few years ago, amid a record drought, scientists noticed something odd. A few of California’s giant sequoias inside Sequoia and Kings Canyon National Parks were dying in ways no one had ever documented – from the top down. When researchers climbed into the canopies, they discovered that beetles had bored into a few branches. By 2019, at least 38 of the trees had died – not a large number, but "concerning because we’ve never observed this before,” says Christy Brigham, the park’s chief of resource management.
Scientists had assumed that stately sequoias, with their bug-repelling tannins, were immune to dangerous pests. Worried experts are investigating whether some mix of increased drought and wildfire, both worsened by climate change, have now made even sequoias susceptible to deadly insect invasions.
If so, these ancient sentinels would be just the latest example of a trend experts are documenting around the world: Trees in forests are dying at increasingly high rates—especially the bigger, older trees. According to a study in the journal Science, the death rate is making forests younger, threatening biodiversity, eliminating important plant and animal habitat, and reducing forests’ ability to store excess carbon dioxide generated by our consumption of fossil fuels. [A]
There is no single direct cause. Decades of logging and land clearing play a role, scientists say. But increasing temperatures and rising carbon dioxide from the burning of fossil fuels have significantly magnified most other causes of tree death. Scientists are documenting longer and harsher droughts, more severe outbreaks of insects and disease, and increasingly catastrophic wildfires.
With 60,000 known tree species on Earth, those shifts are playing out differently across the planet. In central Europe, for instance, “You don’t have to look for dead trees,” says Henrik Hartmann, with Germany's Max Planck Institute for Biogeochemistry. “They’re everywhere.” In one recent year, following a week of excessive heat, hundreds of thousands of beech trees dropped their leaves. Even in colder regions, “You get a couple of hot years and the forests are suffering,” says Hartmann. “There are individual species that are being driven beyond the threshold of what they can handle.” [B]
Just last year, massive fires marched through a dry Australia, smoldered across 7.4 million acres in northern Siberia, and focused the world’s attention on blazes in the Amazon.
The consequences of all these changes around the world are still being assessed. The first national look at tree mortality in Israel showed vast stretches disappearing, thanks largely to scorching heat and wildfires. [C] In a country largely blanketed by stone and sand, forests mean a great deal. Trees support nests for eagles and habitat for wolves and jackals. They hold soil with their roots. [D]
“We’re dealing with a very tough situation. It’s a race to the unknown,” says Tamir Klein at the Weizmann Institute of Science.
What does ‘these ancient sentinels’ in paragraph 3 refer to?
Trong một buổi tọa đàm nhân ngày 8 tháng 3, có 20 đại biểu nữ và 10 đại biểu nam. Ban tổ chức mời 5 đại biểu phát biểu ý kiến. Xác suất để trong 5 phát biểu mời có một hoặc hai phát biểu là của đại biểu nam bằng bao nhiêu?
Read the following passage about the urban shift 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] Landslides are a significant environmental challenge in the northern mountainous provinces of Vietnam, partiCularly during the rainy season. The region, characterized by steep slopes and heavy rainfall, is prone to this natural disaster, which poses serious threats to both the local population and infrastructure. [II] ln recent years, numerous landslides have occurred, often triggered by prolonged periods of heavy rain, resulting in devastating impacts on communities and livelihoods.
The mountainous terrain, combined with deforestation and improper land use, exacerbates the risk of landslides. [III] As farmers clear forests for agriculture, the natural vegetation that stabilizes the soil is lost, making slopes more susceptible to erosion. When heavy rains saturate the soil, it can quickly become unstable, leading to sudden and destructive landslides. [IV]
In response to this growing threat, local authorities and environmental organizations are taking proactive measures to mitigate the risks associated with landslides. Efforts include reforestation projects, improving drainage systems, and raising public awareness about safe practices du ring the rainy season. Additionally, advanced monitoring systems are being implemented to provide early warnings, allowing communities to evacuate before a disaster strikes.
Despite these efforts, the challenges remain significant, and ongoing education and support for sustainable land management practices are crucial for reducing the incidence and impact of landslides in northern Vietnam.
Which of the following best paraphrases the underlined part in paragraph 4?
Người ta truyền cho khí trong xilanh nhiệt lượng 100 J. Khí nở ra thực hiện công 70 J đẩy pit-tông lên. Độ biến thiên nội năng của khí là
Việc ứng dụng vi sinh vật trong thực tiễn không dựa trên đặc điểm nào?
Xét tính đúng sai của các mệnh đề sau:
Một cái thùng hình trụ không có nắp, bên trong thùng có chứa một lượng nước. Một cái nút chai nhấp nhô lên xuống trong thùng (xem Hình 1), biết rằng khoảng cách từ tâm nút chai đến đáy thùng được cho bởi công thức \(s(t) = 50+ cos(t)\) cm, theo thời gian t giây (t≥0).
Hình 1
Nút chai gần với đáy nhất tại thời điểm nào dưới đây?
Đặc điểm của lớp Manti dưới là
Vùng kinh tế nào của Liên bang Nga giàu tài nguyên, công nghiệp phát triển nhưng nông nghiệp còn hạn chế?