1S22S22P63S23P64S2 3d5 . По электронной конфигурации определите положение элемента в ПЕРИОДИЧЕСКОЙ СИСТЕМЕ и заряд ядра атома данного элемента. 1)Iv период , VIIБ группа, + 25
2)vII период , IV группа, + 25
3)Iv период , VIIБ группа, + 55
4)Iv период , VIIБ , + 7

1. I played football yesterday. --> I have played football recently. --> I was playing football yesterday all day long. 2. I worked with my mother at home yesterday. --> I have already worked with my mum. --> I was working with my mom yesterday. 3. I went to the cinema last week. --> I have gone to the cinema recently. --> While I was going to the cinema, my friend broke his leg. 4. I didn't do my homework. --> I haven't done my homework yet. --> I wasn't doing my homework all day long. 5. I made an apple pie one month ago. --> I have already made an apple pie. --> I was making an apple pie when you came home.

Объяснение:

 34 г                                                  Х г                    Х г

 2Na         +         2H2O       =       2NaOH      +        H2

n=2 моль                                    n=2 моль                n=1 моль

М = 23 г/моль                         М = 40 г/моль           М = 2 г/моль

m=46 г                                     m=80 г                       m=2 г

34 г   Na    -    Х г   NaOH

46 г   Na    -   80 г   NaOH

m(NaOH) = 34 * 80 / 46 = 59 г

34 г  Na    -     Х г   Н2

46 г  Na    -   2 г  Н2

m(H2) = 34 *2 / 46 = 1,5 г