Thứ tự một số cặp oxi hoá - khử trong dãy điện hoá như sau: Fe2+/Fe; Cu2+/Cu; Fe3+/Fe2+; Ag+/Ag. Cặp chất không phản ứng với nhau là  

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Một số câu hỏi khác có thể bạn quan tâm.

• Choose the word that has the underlined part pronounced differently from the rest:

   bats                  kids                speaks                cliffs

• Choose the word that has the underlined part pronounced differently from the rest:

   prepares                marries                  excites              halves

• Choose a word that has different stress pattern:

  expensive                 afternoon                  together               description

• Choose a word that has different stress pattern:

  problem               enjoy                decide                 result

• Choose a word that has different stress pattern:

  original                 photographer                 information               believable

• Choose a word that has different stress pattern:

   parents              project                 breakfast                unlike

• Choose a word that has different stress pattern:

  general                  however                 family                motorbike

• Choose the best answer for the following sentence:

  As teenagers, we always _____ each other very well. We still understand each other now.

• Choose the best answer for the following sentence:

  I’m afraid I must ask you both what you _______ yesterday at 10.20 p.m.

• Choose the best answer for the following sentence:

  I ______ him for five years. I wonder where he is.