Lớp | Số electron tối đa |
K | |
L | |
M | |
N |
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
- Lớp K (n=1): $2n^2 = 2(1)^2 = 2$ electron
- Lớp L (n=2): $2n^2 = 2(2)^2 = 8$ electron
- Lớp M (n=3): $2n^2 = 2(3)^2 = 18$ electron
- Lớp N (n=4): $2n^2 = 2(4)^2 = 32$ electron
Câu hỏi liên quan
Trong các câu sau, có bao nhiêu câu là mệnh đề?
(1): Số 3 là một số chẵn.
(2): 2x+1=3.
(3): Các em hãy cố gắng làm bài thi cho tốt.
(4): 1<3⇒4<2.
Tìm các nghiệm \(\left( x;y \right)\) của bất phương trình \(\frac{x}{2}+\frac{y}{3}-1\le 0\). Trong đó \(x,y\) là các số nguyên dương. Tính \(x+y\).
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:
For many people who live in cities, parks are an important part of the landscape. They provide a place for people to relax and play sports, as well as a refuge from the often harsh environment of a city. What people often overlook is that parks also provide considerable environmental benefits.
One benefit of parks is that plants absorb carbon dioxide - a key pollutant - and emit oxygen, which humans need to breathe. According to one study, an acre of trees can absorb the same amount of carbon dioxide that a typical car emits in 11,000 miles of driving. Parks also make cities cooler. Scientists have long noted what is called the Urban Heat Island Effect: building materials such as metal, concrete, and asphalt absorb much more of the sun’s heat and release it much more quickly than organic surfaces like trees and grass. Because city landscapes contain so much of these building materials, cities are usually warmer than surrounding rural areas. Parks and other green spaces help to mitigate the Urban Heat Island Effect.
Unfortunately, many cities cannot easily create more parks because most land is already being used for buildings, roads, parking lots, and other essential parts of the urban environment. However, cities could benefit from many of the positive effects of parks by encouraging citizens to create another type of green space: rooftop gardens. While most people would not think of starting a garden on their roof, human beings have been planting gardens on rooftops for thousands of years. Some rooftop gardens are very complex and require complicated engineering, but others are simple container gardens that anyone can create with the investment of a few hundred dollars and a few hours of work.
Rooftop gardens provide many of the same benefits as other urban park and garden spaces, but without taking up the much-needed land. Like parks, rooftop gardens help to replace carbon dioxide in the air with nourishing oxygen. They also help to lessen the Urban Heat Island Effect, which can save people money.
In the summer, rooftop gardens prevent buildings from absorbing heat from the sun, which can significantly reduce cooling bills. In the winter, gardens help hold in the heat that materials like brick and concrete radiate so quickly, leading to savings on heating bills. Rooftop vegetable and herb gardens can also provide fresh food for city dwellers, saving them money and making their diets healthier. Rooftop gardens are not only something everyone can enjoy, they are also a smart environmental investment.
Question 37: Using the information in paragraph 2 as a guide, it can be inferred that ______.
Đồ thị độ dịch chuyển – thời gian trong chuyển động thẳng của một vật được vẽ ở hình dưới. Xác định độ dịch chuyển của xe sau 10 giây chuyển động
Bảng xét dấu nào sau đây là bảng xét dấu của tam thức \(f(x) = x^2 + 2x + 1\) là:
Read the following passage about the impact of social media on mental health and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions
[I] In recent years, social media platforms have become a central part of daily life, offering users countless ways to connect, share, and communicate. [II] While these platforms offer many advantages, experts have noted rising concerns about their effects on mental health, particularly among young people (Smith & Anderson, 2018). [III] Studies reveal that excessive social media use can contribute to feelings of anxiety, depression, and loneliness, despite its intention to promote connection and social interaction (Twenge & Campbell, 2019). [IV]
A primary reason for these mental health concerns is the tendency for social media users to compare themselves to others. Platforms like Instagram and Facebook often highlight idealized lifestyles, leading users to feel inadequate about their own lives. Additionally, the constant notifications and messages contribute to a "fear of missing out," or FOMO, which keeps individuals in a cycle of checking their phones, often reducing the quality of sleep and overall well-being.
There is also a growing body of research suggesting a link between social media use and decreased attention spans. When users frequently switch between apps and notifications, their ability to focus for extended periods may diminish (Rosen, 2019). This shift in attention can interfere with productivity, especially in academic and professional settings, where sustained focus is essential.
Addressing these challenges requires a multi-faceted approach. Some mental health professionals suggest limiting screen time and setting boundaries, such as "device-free" hours before bedtime. Others recommend engaging in offline activities, like reading or exercising, to reduce dependence on social media and build healthier habits. According to psychologists, such strategies can bu mental resilience and allow for more meaningful, balanced relationships (Robinson & Smith, 2020).
According to paragraph 2, which of the following is NOT an effect of social media on mental health?
Giá điện được thay đổi từ ngày 04/5/2023 đến trước ngày 9/11/2023 đã quy định rõ về giá bán lẻ điện cho các đơn vị bán lẻ điện đối với nhóm khách hàng sử dụng điện sinh hoạt gồm 6 bậc như sau:
Sau khi đo được số điện tháng 9 năm 2023 nhà mình đã dùng, Mai biết được nhà mình đã dùng hết 210kWh, khi đó số tiền điện mà nhà Mai cần phải đóng (chưa tính 8% thuế giá trị gia tăng) là:
Việc các nhà phân phối hàng hóa mua, trữ hàng và bán lại cho các đại lí hoặc nhà bán lẻ giúp lưu thông hàng hóa hiệu quả thể hiện đặc điểm của chủ thể nào trong nền kinh tế?
Tổng số orbital trong lớp M là?
Read the following advertisement 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 1 to 6.
UNBREAKABLE SPIRIT: AN EVENING WITH NICK VUJICIC
We are thrilled to announce that (1) ______ Nick Vujicic will be visiting our community for an exclusive seminar (2) ______ to inspire, empower, and create lasting change. This once-in-a-lifetime event will offer attendees the opportunity to hear Nick's powerful story of resilience, faith, and perseverance firsthand. Born without limbs, Nick has transformed his circumstances into a source of (3) ______. He has spoken to millions of people around the globe, spreading messages of hope, and the courage to turn obstacles (4) ______ opportunities. Nick’s dynamic and engaging approach has (5) ______ a lasting impact on audiences of all ages and backgrounds. Participants will gain practical strategies for overcoming challenges, achieving personal and professional goals. This event is organized (6) ______ personal growth, motivate change, and cultivate unity. Join us for an unforgettable experience. Space is limited, so be sure to reserve your spot today!
Hai mươi năm đầu sau Chiến tranh thế giới thứ hai, quốc gia nào trở thành trung tâm kinh tế-tài chính lớn nhất thế giới?
Hai xe cùng xuất phát từ hai bến xe A và B cách nhau 20 km trên một đoạn đường thẳng. Nếu hai xe chạy ngược chiều thì chúng sẽ gặp nhau sau 15 phút. Nếu hai xe chạy cùng chiều thì chúng sẽ đuổi kịp nhau sau 1 giờ. Vận tốc của mỗi xe lần lượt là
Thế nào là sinh trưởng của cơ thể động vật?
Chiến thắng nào của nghĩa quân Tây Sơn đánh dấu sự thất bại hoàn toàn của quân Xiêm năm 1785?
Phương trình tổng quát của đường thẳng đi qua điểm \(A(1; - 3)\) và có vectơ pháp tuyến \(\vec n(2; - 1)\) là?
Cho hình bình hành ABCD, \(\vec u{\rm{ \;}} = \overrightarrow {AC} {\rm{ \;}} + \overrightarrow {BD} \). Khẳng định nào sau đây đúng?
Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.
Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes accustomeLoud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased.
Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each other.
Based on the passage, how does noise affect psychological and physical health in industrial societies?
- Trong mỗi ý a), b), c), d) ở mỗi câu, thi sinh chọn đúng hoặc sai
Cho hàm số \({\rm{f}}({\rm{x}}) = {\rm{x}} + \frac{1}{{{\rm{x}} + 2}}.\)
Trong không gian Oxyz, cho ba điểm \(A(2;3;3), B(0;5;5), C(1;1;1)\). Gọi \((P)\) là mặt phẳng đi qua \(C\) sao cho \((P)\) cách \(A\) một đoạn bằng 3 và cách \(B\) một đoạn bằng 5. Tính khoảng cách từ \(O\) đến \((P)\). Làm tròn kết quả đến hàng phần trăm.
Nhận định nào dưới đây thể hiện chức năng của Ủy ban nhân dân?