Answer:
|A| = √(Ax)^2 + (Ay)^2
|A| = √(7.6)^2 + (-6.4)^2
|A| = √98.72
|A| = 9.9
(a) 
The energy of a photon is given by:

where
is the Planck constant
is the speed of light
is the wavelength
For the microwave photon,

So the energy is

And converting into electronvolts,

(b) 
For the energy of the photon, we can use the same formula:

For the visible light photon,

So the energy is

And converting into electronvolts,

(c) 
For the energy of the photon, we can use the same formula:

For the x-ray photon,

So the energy is

And converting into electronvolts,

<span>The star's main fuel during its lifetime is hydrogen. It is said that a star is composed of 97% hydrogen and 3% helium. Once the hydrogen of a star is gone, the star becomes old because it burns hydrogen during its lifetime.</span>