Запишите уравнения реакций, с помощью которых можно осуществить следующие превращения: Na -> Na2O -> NaOH -> Na2CO3 -> Na.

K + H2O =

Cu + FeSO4 =

Al + C =

Fe + H2SO4 = 

Вставьте much или many.
 
Example: Please don't put ... pepper on the meat. - Please don't put much pepper on the meat.
 
1. Please don't put ... pepper on the meat. 2. There were ... plates on the table. 3. I never eat I... bread with soup. 4. Why did you eat so ... ice-cream? 5. She wrote us ... letters from the country. 6. ... of these students don't like to look up words in the dictionary. 7. ... in this work was too difficult for me. 8. ... of their answers were excellent. 9. ... of their conversation was about the institute. 10. There are ... new pictures in this room. ll. There are ... teachers at our school, and ... of them are women. 12. ... of these plays are quite ... new. 13. Thanks awfully for the books you sent me yesterday.  Don't mention it, it wasn't ... bother. 14. ... of her advice was useful. 15. He had ... pairs of socks.

Две щели находятся на расстоянии 0,20 мм друг от друга и отстоят на расстоянии 1,5 м от экрана.На щели падает поток монохроматического света l=500 нм от удаленного источника.Найдите расстояние между соседними интерференционными полосами