Answer : The energy of one photon of hydrogen atom is, 
Explanation :
First we have to calculate the wavelength of hydrogen atom.
Using Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant = 10973731.6 m⁻¹
= Higher energy level = 3
= Lower energy level = 2
Putting the values, in above equation, we get:


Now we have to calculate the energy.

where,
h = Planck's constant = 
c = speed of light = 
= wavelength = 
Putting the values, in this formula, we get:


Therefore, the energy of one photon of hydrogen atom is, 
Time taken by the water balloon to reach the bottom will be given as

here we know that


now by the above formula



now in the same time interval we can say the distance moved by it will be


so it will fall at a distance 15.7 m from its initial position
Among the choices the one that most likely cause a sound wave is C or the a spoon hitting the side of a bowl while mixing <span>because that's going to make a sound.
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Answer:
Explanation:
according to third equation of motion
2as=vf²-vi²
vf²=2as+vi²
vf=√2as+vi²
vf=√2as+vi
vf=√2*2*4+3
vf=√16+3
vf=4+3=7
so final velocity is 7 m/s