5.
1. A Very sick and miserable boy of nine years - Very Unhappy.
2. When I put my hand on his forehead I knew he had a fever. - A high temperature.
3. HE seemed very detached from... - Didn't pay atttention to.
4. He seemed very detached from what was going on. - What was happening aroUnd him.
5. ... he was a little lightheaded... - was not able to think clearly.
6. ...but I can't keep from thinking. - stop myself thinking.
7. He was holding tight on to himself about something. - Trying to keep his emotions tO himself.
6.
Yes, the story had a happy ending. The boy thought that he was going to die. It was because of that he didn't know the difference between the different thermometeres.
7.
The temperature of the boy was 38,9 C.
Положение и свойства элементов в таблице Д.И.Менделеева определяется числом протонов.
У калия 19 протонов, а у аргона - 18. Следовательно это разные элементы.
(Одинаковые массы у этих элементов - случайное совпадение.)