Question

Red and green light have wavelengths of about 650 nm and 490 nm, respectively. which light has the highest frequency

Answer 1

1. Red, orange, yellow, green, violet. 
2. When elections return to their normal, or ground-state position, engery is emitted. When energy is absorbed, electrons within the atoms of substances are excited to higher positions of potential energy. 
3. Green light has a higher frequency and a higher energy. (Lower wavelengths mean higher energy and frequency both.) 
4. No, a spectroscope could not be used to detect that emission because 285 nm is not in the visible light color spectrum (400-about 700 nm). ((this one I am least sure about, someone else helped with this one)) 
5. Should be green light because that is 495-570nm. 
6. the slit in the spectroscope allows a narrow, collimated beam of light to be admitted. 

Answer 2

Answer : Green light.

Explanation :

Wavelength of the red light, $\lambda=650\ nm=650\times 10^{-9}\ m$  

Wavelength of the green light, $\lambda=490\ nm=490\times 10^{-9}\ m$

The frequency of the red light is given by :

$\nu=\dfrac{c}{\lambda}$

$\nu_r=\dfrac{3\times 10^8\ m/s}{650\times 10^{-9}}$

$\nu_r=4.6\times 10^{14}\ Hz$

The frequency of the green light is given by :

$\nu=\dfrac{c}{\lambda}$

$\nu_g=\dfrac{3\times 10^8\ m/s}{490\times 10^{-9}}$

$\nu_g=6.12\times 10^{14}\ Hz$

So, green light has highest frequency.