선생님이 미국에서 가르쳐서 질문에 답이 늦어서 미안해요.  다음번에는 페이지 number 보다는 레슨 number를 알려주면 좋겠어요.  

1. 22.4 liter is correct.

2. less number of neutron --> less mass number --> low boiling point and melting point

3. Becuase the separation of ions based on mass difference.  It is okay to written as mass number.  

4.  All electromagnetic radiation moves at the same speed, namely, the speed of light.  So the wavelength and frequency of electromagnetic radiation are always related in a straightforward way.  If the wavelength is long, fewer cycles of the wave pass a given point per second, and the frequency is low and vice versa. 

5. It does not matter to switch.

6.  Zn does not have any unpaired electons.  

7. The number of neutons and number of protons are not always the same.  If we only consider the mass of the proton, potassium should be heavier, but the atomic mass of the argon is heavier becuase argon has more number of neutons than potassium.  

8.    2809= 3.10 × 30 + 28x +29(96.9 – x);

       % 28Si =(93 + 2810.1 – 2809) = 94.1 %;

      When you add all three, the sum should be zero.