Trong một phân tích quang phổ phát xạ của nguyên tử hydro, người ta thấy có ba vạch màu. Quang phổ phát xạ trên có bao nhiêu vạch? 

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Choose the best answer for the following sentence:

  In spite of his illness, he ____________.
  
  

• Choose the best answer for the following sentence:

  Internet brings us too much information ____________ it makes us passive for we don't have to think much.
  
  

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

  make                 fame                 cake                  bad

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

  fat                     private                       cat                      mad

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

  spend                  send                      lend                   become

• Choose the best answer for the following sentence:

  Look! Someone ___________ the coffee on the keyboard.
  
  

• Choose a word that has different stress pattern:

  experience                 favourite                  subject                  primary

• Choose the best answer for the following sentence:

  Nghia: “Where _____________ born?”

  Ngoc: “In Kim Lien, Nam Dan”
  
  

• Choose a word that has different stress pattern:

  interview                   background                      scientific                      secondary

• Choose the best answer for the following sentence:

  He failed the exam to university last year. Since then he ______________ very hard
  the next entrance examination.