Answer:
the heat always transfers from high temperature to low temperature body without aid of any external energy to this law the heat transfers from cup of coffee to the person body until both bodies reaches to the equilibrium state
Explanation:
The amount of energy of a photon is proportional to the frequency.
1. 
First of all, let's convert the energy of the absorbed photon into Joules:

The energy of the photon can be rewritten as:

where
h is the Planck constant
c is the speed of light
is the wavelength of the photon
Re-arranging the formula, we can solve to find the wavelength of the absorbed photon:

2. 1.24 eV
In this case, when the electron jumps from the n=4 level to the n=3 level, emits a photon with wavelength

So the energy of the emitted photon is given by the formula used previously:

and using

we find

converting into electronvolts,

EDIT: an issue in Brainly does not allow me to add the last 2 parts of the solution - I have added them as an attachment to this post, check the figure in attachment.
Answer:
Nebulae contribute more to stellar formation than other regions because:
Explanation:
A.They have an unlimited supply of hydrogen.
B. They are believed to be rich in hydrogen and helium.
C. They have a three strong gravitational pull.
This are the reasons that Nebulae contribute more to stellar formation than other regions.
Answer:
B
Explanation:
<em>A. His speed is 0 m/s
</em>
<em>B. His velocity is 12 m/s
</em>
<em>C. His velocity is 0 m/s
</em>
<em>D. His acceleration is 12 m/s</em>
Total distance traveled by John = 120 + 120 = 240 meters
Total time taken by John to cover the distance = 10 + 10 = 20 s
<em>Average speed of John = total distance traveled/total time taken</em>
= 240/20 = 12 m/s
Hence, the average speed/velocity of John throughout the journey is 12 m/s.
The correct option is B.