Phốt pho  phóng xạ  với chu kỳ bán rã T = 14,2 ngày và biến đổi thành lưu huỳnh (S).Sau 42,6 ngày kể từ thời điểm ban đầu, khối lượng của một khối chất phóng xạ  còn lại là 2,5g. Tính khối lượng ban đầu của nó.          

Chia sẻ

Một số câu hỏi khác có thể bạn quan tâm.

• Choose one sentence that has the same meaning as the root one:

  The work is well- paid. He wants to apply for it.
  
  

• Choose one sentence that has the same meaning as the root one:

  The flat is on the second floor. He lives in the flat.
  
  

• Choose one sentence that has the same meaning as the root one:

  ''You had better not cross the forest at night,'' Peter said.

   

• Choose the correct sentence which is built from the words and phrases given:

  right / you / see / come / to / will / I / my / after / exam

   

   

• Choose the correct sentence which is built from the words and phrases given:

  must / now / say /, / ''Happy Birthday'' / and / I

   

• Choose a word that has different stress pattern:

   volunteer                 agreement                   experience                   remedial

• Choose a word that has different stress pattern:

   develop               discover                  different                 promotion

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

   obliged                environment                    literacy                  divide

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

  attain              main               certain               campaign

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

   developed                    discovered                       worked                     expressed