(W/pay) now or later?
7. Do you think
(l/apply) for this job?
8 What do you think (l/write) in this space on the form?
(l/eat) any more cake. I've already eaten too much.
10 This food is terrible.
(Welcomplain) to the manager
11 Which shirt do you think (l/buy)?
kes ve already eaten toom
решение и перевод
3) w(Ca) = 40%; w(C) = 12%; w(O) = 48%.
4) w(Cu) = 79%; w(O) = 20% или 21%.
5) w(Al) = 52%; w(O) = 47% или 48%.
Объяснение:
Задача №3.
CaCO
Ar(Ca) = 40
Ar(C) = 12
Ar(O) = 16
w(Ca) = 40 / 100 = 0,4 или 40%
w(C) = 12 / 100 = 0,12 или 12%
w(O) = 48 / 100 = 0,48 или 48%
или
w(O) = 100% - (40% + 12%) = 100% - 52% = 48%
Задача №4.
CaO
Ar(Ca) = 40
Ar(O) = 16
Mr(CaO) = 40 + 16 = 56
w(Ca) = 40 / 56 = 0,71 или 71%
w(O) = 16 / 56 = 0,28 или 28%
или
w(O) = 100% - 71% = 29%
НО, у вас указано оксид меди (II) и формула CaO, хотя оксид меди - это CuO - поэтому решу на всякий случай CuO.
CuO
Ar(Cu) = 63,5
Ar(O) = 16
Mr(CuO) = 63,5 + 16 = 79,5
w(Cu) = 63,5 / 79,5 = 0,79 или 79%
w(O) = 16 / 79,5 = 0,20 или 20%
или
w(O) = 100% - 79% = 21%
Задача №5.
Ar(O) = 16
Ar(Al) = 27
Mr(
) = 27*2 + 16*3 = 54 + 48 = 102
w(Al) = 54 / 102 = 0,52 или 52%
w(O) = 48 / 102 = 0,47 или 47%
или
w(O) = 100% - 52% = 48%