Ответ:
1. When most people can't read. - illiteracy
2. The opposite of war. - peace
3. What you get when chemicals go into rivers. - pollution
4. People live in this when they are very poor. - poverty
5. When people treat others badly because of the colour of their skin. - racism
6. A problem affecting children when they don't have enough eat. - hunger
7. When countries fight each other. - war