<u>Answer:</u> The energy of one photon of the given light is 
<u>Explanation:</u>
To calculate the energy of one photon, we use Planck's equation, which is:

where,
= wavelength of light =
(Conversion factor:
)
h = Planck's constant = 
c = speed of light = 
Putting values in above equation, we get:

Hence, the energy of one photon of the given light is 
Explanation:
The sum of total number of protons present in an element is known as atomic number of the element.
- As atomic number of Cs is 55.
And, it is known that for a neutral atom the number of protons equal to the number of electrons.
Since, no charge in present on given Cs atom it means that it is neutral in nature. Hence, number of protons and electrons present in Cs are 55.
- For Ba, it is also neutral in nature and atomic number of barium is 56. Hence, number of protons and electrons present in Ba are 56.
- For S, there is no charge on it so it is also neutral in nature. Atomic number of S is 16. Hence, number of protons and electrons present in S are 16.
Gravitational force will increase with greater mass