В сосуд, содержащий 10 литров 15-процентного водного раствора некоторого вещества добавили 15 литров 10-процентного одного раствора этого же вещества. Сколько процентов составит концентрация получившегося раствора? С решением плиз)

Расположите элементы 4-го периода в порядке возрастания их неметалических свойств: 1) Se; 2) Ge; 3) Br; 4) As; 5) Zn.

при какой температуре находился газ, если при его изобарном нагреве на 300 К, объем возрос в 2,5 раза.

Нужен точный перевод.

I'm fine . My life here is very busy and interesting . I'm learning a lot of about England . It's very different from Russia . My first big surprise is the bathroom . There are two taps ! One for hot water and one for cold water. When I wash my hands I must put the plug in the plug hole and mix the water in the basin .
The second shock is English weather.
It's November, but it's not cold. There is no snow either, but Christmas is in the air because there are Christmas trees and decorations in all the shops. It's funny . The grass is green , there are still roses in the garden, and the weather is very rainy. It's about 15 degrees and i wear my sweater . But you must see the English. They don't feel cold. Some people still wear sandals and T-shirts and don't wear any warm clothes. But it's not summer . At night the house is cold .
Central hating is expensive and they don't use it very often. So i go to bed with a hot water bottle