Thực hiện các thí nghiệm sau         

(1) Cho bột Al vào dung dịch NaOH (dư).         

(2) Điện phân dung dịch NaCl bằng điện cực trơ, không màng ngăn xốp.         

(3) Cho dung dịch KI vào dung dịch chứa Na2Cr2O7 và H2SO4.         

(4) Dẫn luồng khí NH3 qua ống sứ chứa CrO3.         

(5) Cho bột Fe vào lượng dư dung dịch FeCl3.

Số thí nghiệm thu được đơn chất là.  

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Find a mistake in the four underlined parts of the sentence and correct it:

  A friend who support his own friends through emotional difficulties is a true friend.

• Find a mistake in the four underlined parts of the sentence and correct it:

  There are many competitions which having positive effects on competitors.

• Find a mistake in the four underlined parts of the sentence and correct it:

  I am looking forward to see the final of the elocution contest which will be organized at the auditorium.

• Find a mistake in the four underlined parts of the sentence and correct it:

  Population density is the highest in the Red River Delta, 1,136 people per km², and the

  lower in the northwest with only 62 people per km².

• Find a mistake in the four underlined parts of the sentence and correct it:

  Agricultural land per each capita decreased from 0.25 hectares in 1943 to 0.10 ha in 1995.

• Find a mistake in the four underlined parts of the sentence and correct it:

  Rapid population growth, migration, and urbanize in Vietnam have placed new pressure on

  the environment, particularly as a result of forest exploitation, and depletion of water

  resources.

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

  teacher                   beat                   breakfast                     eating

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

  passenger                  several                  begin                    repair

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

  meeting                      weekly                    engineer                       free

• Choose a word that has different stress pattern:

  alternative                  announce                  absolute                    arrive