1. Hợp chất A có phân tử gồm 2 nguyên tử X và 3 nguyên tử Y. Tỉ lệ khối lượng của X và Y là 7:3 . Phân tử khối của hợp chất là 160. Hỏi :

a. Nguyên tố X và Y là?

b. Viết CTHH của hợp chất A

Cho bt Cu = 64,Cl=35,5,O=16,S=32,H=1,Na=23,C=12

2.Một hợp chất có phân tử gồm một nguyên tử A liên kết với 4 nguyên tử H và nặng bằng nguyên tử O

a. Tính PTK của hợp chất

b. Xác định tên và ký hiệu của nguyên tố A và CTHH của hợp chất

c. Tính hóa trị của A trong hợp chất trên

3.Viết sơ đồ công thức của hợp chất CaSO₄và Mg (H₂PO₄)₂

Read the passage carefully and choose correct answer for each question below.

Education is another area of social life in which information technology is changing the way we communicate. Today's college students may not simple sit in a lecture or a library to learn about their field. Through their computers and the wonders of virtual reality they can participate in lifelike stimulated experiences. Consider the following scenario of the future of education made possible through developments in information technology.

For children over the age of 10, daily attendance at schools is not compulsory. Some of the older children attend school only once or twice a week to get tutorial support or instruction from a teacher. For the most part, pupils are encouraged to work online from home. Students should complete a minimum number of study hour per year; however, they may make up these hours by studying at home at times that suit their family schedule. They can log on early or late in the day and even join live classes in other countries. In order to ensure that each student is learning adequately, computer software will automatically monitor the number hours a week each student studies online as well as student's learning materials and assessment activities. Reports will be available for parents and teachers. The software can then identify the best learning activities and conditions for each individual student and generate similar activities. It can be also identify areas of weak achievement and produce special programs adjusted to the students' needs.

What can't the software do?

A. Find out the best activities for the students

B. Design materials for the students

C. Identify weaknesses of the students

D. Monitor the time the students learn