Answer: a) 
b) 
Explanation: Visible light is a form of electromagnetic wave.
Wavelength is defined as the distance between two successive crests of a wave. It is represented as symbol
.
Frequency is defined as the number of complete cycles happening per second. It is represented by the symbol
.
Wavelength and Frequency follow inverse relation,

where, c = speed of light = 
Wavelength and frequency of a wave is usually expressed in a range.
a) 
b) 
D. a change in color of a substance
Answer:
I think #3 might be the answer .
Because in #1 atomic mass tells mass .
#4 Atomic number doesnot only tell about the electrons atom has
It tells you how many protons it has and because the number of protons =electrons it tells you also the number of electrons.
Late answer:
Chromosphere.