gọi X1, X2 là 2 đồng vị của X
X1 = 35 + 44 = 79
X2 = 35 + (44 + 2) = 81
mà X1/X2 = 27/23
=> 100% X có 54% X1, 46%X2
=> X = (79.54 + 81.46)/100 = 79,92
nguồn facebook
Lớp 8
Nam: Hello
Mrs. Vui: Nam, it’s Mom
Nam: Hi, Mom
Mrs. Vui: I'm going to be home late tonight. I have to go and visit Grandma after work.
Nam: What time will you be home?
Mrs Vui: I’ll be home after dinner. I'm sorry, but you’ll have to cook dinner yourself.
Nam: All right.
Mrs. Vui: There’s...