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,
Answer:
speed of light simulating traveling at the speed of light. Speed of light, speed at which light waves propagate through different materials. In particular, the value for the speed of light in a vacuum is now defined as exactly 299,792,458 metres per second
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium
Yes, an increase in temperature is accompanied by an increase in pressure. Temperature is the measurement of heat present and more heat means more energy. Molecules in hotter temperatures move faster and more often, eventually moving into the gaseous phase. The molecules would fill the container, and the hotter it got the more they would bounce off the walls, pushing outward, increasing the pressure.
I suppose you could measure this with some kind of loosely inflated balloon and subject it to different temperatures and then somehow measure the size/pressure of it.
