The question ask to calculate and choose among the following is the distance of the microphone from the left - most speaker in order to pick up the loudest sound and the best answer would be letter C. I hope you are satisfied with my answer and feel free to ask for more if you have questions and further clarifications
Answer:
The number of free electrons per cubic meter is 
Explanation:
It is given that,
The number of free electrons per cubic meter is, 1.3
Electrical conductivity of metal, 
Density of metal, 
Atomic weight, A = 107.87 g/mol
Let n is the number of free electrons per cubic meter such that,


Where
is the density of silver atom
is the Avogadro number
A is the atomic weight of silver


or

Hence, this is the required solution.
Answer:
Geocentric theory: Earth is the center of the universe.
Heliocentric theory: The Sun is the center of the universe.
Explanation:
The geocentric theory was formulated by Aristotle and says that the earth is the center of the universe and the other planets and stars including the sun revolve around it.
On the other hand, Copernicus with his heliocentric theory states that the sun is the center of the universe and the planets revolve around it.