Nguyên tử nguyên tố Y có tổng số hạt cơ bản là 48, trong đó số hạt mang điện gấp đôi số hạt không mang điện. Nguyên tố Y là
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
Từ (1) và (2) suy ra: $2p + n = 48$ (4) Từ (2) và (3) suy ra: $2p = 2n$ hay $p = n$ (5)
Thay (5) vào (4) ta được: $2p + p = 48$ <=> $3p = 48$ <=> $p = 16$. Vậy nguyên tố Y có số proton là 16, đó là Magnesium (Mg).
Câu hỏi liên quan
Millions of people are using cellphones today. In many places, it is actually considered unusual not to use one. In many countries, cellphones are very popular with young people. They find that the phones are more than a means of communication - having a mobile phone shows that they are cool and connected.
The explosion in mobile phone use around the world has made some health professionals worrieSome doctors are concerned that in the future many people may suffer health problems from the use of mobile phones. In England, there has been a serious debate about this issue. Mobile phone companies are worried about the negative publicity of such ideas. They say that there is no proof that mobile phones are bad for your health.
On the other hand, medical studies have shown changes in the brain cells of some people who use mobile phones. Signs of change in the tissues of the brain and head can be detected with modern scanning equipment. In one case, a traveling salesman had to retire at young age because of serious memory loss. He couldn't remember even simple tasks. He would often forget the name of his own son. This man used to talk on his mobile phone for about six hours a day, every day of his working week, for a couple of years. His family doctor blamed his mobile phone use, but his employer's doctor didn't agree.
What is it that makes mobile phones potentially harmful? The answer is radiation. High-tech machines can detect very small amounts of radiation from mobile phones. Mobile phone companies agree that there is some radiation, but they say the amount is too small to worry about.
As the discussion about their safety continues, it appears that it's best to use mobile phones less often. Use your regular phone if you want to talk for a long time. Use your mobile phone only when you really need it. Mobile phones can be very useful and convenient, especially in emergencies. In the future, mobile phones may have a warning label that says they are bad for your health. So for now, it's wise not to use your mobile phone too often.
What does the word “They” in paragraph 2 refer to?
Trong trường hợp dưới đây, những yếu tố nào đã ảnh hưởng đến lượng cung hàng hóa trên thị trường tiêu dùng?
"Doanh nghiệp T chuyên sản xuất, kinh doanh những thực phẩm chế biến từ thịt lợn. Gần đây, hoạt động sản xuất của doanh nghiệp gặp khó khăn do giá của các yếu tố đầu vào (con giống, cám,..) tăng khiến chi phí sản xuất và giá bán sản phẩm bị đẩy lên cao. Số lượng các đơn đặt hàng cũng giảm sút do thị trường xuất hiện nhiều nhà cung ứng sản phẩm cùng loại".
Thể ba nhiễm của một loài có 25 NST trong mỗi tế bào sinh dưỡng. Hỏi ở thể lưỡng bội của loài này có bao nhiêu NST trong mỗi tế bào sinh dưỡng?
Cho hàm số \(y=f(x)\) có bảng biến thiên như sau:
Diện tích tam giác tạo bởi 3 điểm cực trị của đồ thị hàm số \(y=f(x)\) là:
So với các môn học khác, môn Địa lí có điểm khác biệt gì?
Khi sử dụng các thiết bị điện trong phòng thí nghiệm Vật lí chúng ta cần lưu ý điều gì?
Cho hàm số \(y = {\cot ^2}\frac{x}{4}\). Khi đó nghiệm của phương trình y'=0 là
Người sáng lập học phái Nho gia là
Đâu là phương thức sinh sản vô tính phổ biến nhất ở vi sinh vật?
Số đường thẳng đi qua điểm và tiếp xúc với đồ thị hàm số là?
Tốc độ trung bình bằng độ lớn vận tốc trung bình khi nào?
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 thefollowing questions from 13 to 17.
a. Kate: I’m starting with landscapes, but I want to try portraits eventually.
b. Kate: I’ve decided to take up painting as a hobby.
c. Anna: That sounds like a lot of fun!
d. Kate: Yeah, it helps me relax after work.
e. Anna: What kind of painting are you doing?
Viết tập hợp D gồm các chữ cái có trong từ “TOKYO”.
Phát biểu nào sau đây là không đúng về 82206Pb?
Nội dung nào sau đây phản ánh đúng vai trò của Sử học đối với các ngành khoa học tự nhiên và công nghệ?
Dầu và mỡ được cấu tạo bởi những thành phần nào?
Read the following passage about world festivals and mark the best answer to the questions from 11 to 18.
World festivals have a big impact on young people today. Festivals such as Christmas, Diwali, Halloween, and Chinese New Year are celebrated across the globe, bringing people together. Young people especially enjoy these events because they offer a chance to have fun, learn about different cultures, and develop a global mindset.
Festivals help young people appreciate diversity. Attending a festival from another culture teaches them new traditions, food, music, and art. For example, attending the Rio Carnival or the Holi Festival of Colors can give young people an exciting experience of new cultures. They learn to respect and understand people from different backgrounds, which is important in today’s world.
Another impact is that festivals allow young people to express themselves creatively. Many festivals include costumes, dances, and music that encourage self-expression. For instance, during Halloween or a music festival like Coachella, young people often wear creative outfits or costumes that reflect their personalities. This makes them feel confident and allows them to experiment with new styles.
Festivals also offer opportunities for young people to connect with others. Meeting people at festivals, whether in person or online, helps them build friendships and networks. Social media plays a big role in this, as many young people post about their experiences, spreading awareness of the festivals they attend.
Overall, world festivals provide many learning and social experiences for young people, helping them grow into more open-minded and creative individuals.
Which of the following best paraphrases the sentence in paragraph 3 below?
"Young people often wear creative outfits or costumes that reflect their personalities."
Cho các yêu cầu xây dựng chuồng nuôi cần đảm bảo dưới đây:
(1) Vị trí cao ráo, thoáng mát, thoát nước tốt, xa khu dân cư, chợ, trường học,…
(2) Tính toán phù hợp với quy mô chăn nuôi.
(3) Đầy đủ, phù hợp với đối tượng vật nuôi và từng giai đoạn.
(4) Cao 3 – 4 m để đảm bảo thông thoáng.
(5) Đảm bảo đủ diện tích cho từng con vật nuôi.
Trong các yêu cầu xây dựng chuồng nuôi trên, những yêu cầu xây dựng chuồng nuôi nào cần đảm bảo về mặt bằng xây dựng?
Số proton và số neutron trong hạt nhân nguyên tử \(_{80}^{201}X\) là
Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer.
Global Issues: Gender Equality and Women’s Empowerment
Gender equality means that men and women have equal power and equal opportunities for financial independence, education, and personal development. Women's empowerment is a critical aspect of achieving gender equality. It includes increasing a woman's sense of self-worth, her decision-making power, her access to opportunities and resources, her power and control over her own life inside and outside the home, and her ability to effect change. Yet gender issues are not focused on women alone, but on the relationship between men and women in society. The actions and attitudes of men and boys play an essential role in achieving gender equality.
Education is a key area of focus. Although the world is making progress in achieving gender parity in education, girls still make up a higher percentage of out-of-school children than boys. Approximately one quarter of girls in the developing world do not attend school. Typically, families with limited means who cannot afford costs such as school fees, uniforms, and supplies for all of their children will prioritize education for their sons. Families may also rely on girls' labor for household chores, carrying water, and childcare, leaving limited time for schooling. But prioritizing girls' education provides perhaps the single highest return on investment in the developing world. An educated girl is more likely to postpone marriage, raise a smaller family, have healthier children, and send her own children to school. She has more opportunities to earn an income and to participate in political processes, and she is less likely to become infected with HIV.
Women's health and safety is another important area. HIV/AIDS is becoming an increasingly impactful issue for women. This can be related to women having fewer opportunities for health education, unequal power in sexual partnership, or as a result of gender-based violence. Maternal health is also an issue of specific concern. In many countries, women have limited access to prenatal and infant care, and are more likely to experience complications during pregnancy and childbirth. This is a critical concern in countries where girls marry and have children before they are ready; often well before the age of 18. Quality maternal health care can provide an important entry point for information and services that empower mothers as informed decision-makers concerning their own health and the health of their children.
A final area of focus in attaining gender equality is women's economic and political empowerment. Though women comprise more than 50% of the world's population, they only own 1% of the world's wealth. Throughout the world, women and girls perform long hours of unpaid domestic work. In some places, women still lack rights to own land or to inherit property, obtain access to credit, earn income, or to move up in their workplace, free from job discrimination. At all levels, including at home and in the public arena, women are widely underrepresented as decision-makers. In legislatures around the world, women are outnumbered 4 to 1, yet women's political participation is crucial for achieving gender equality and genuine democracy.
According the passage, what is the meaning of “gender equality”?