The answer should be D) electrical
solution:
You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. 

Answer:
francium
Explanation:
the atomic radius increases from top to bottom in a group, and decreases from left to right across a period.
Answer:
did you get the answer???
Explanation:
I really need help