Answer:
Option A
The cost of keeping the semiconductor below the critical temperature is unreasonable
Explanation:
First of all, we need to understand what superconductors are. Superconductors are special materials that conduct electrical current with almost zero resistance. This means that there is little or no need for a voltage source to be connected to them. As a matter of fact, once a superconductor is connected to a power supply, one can remove the power supply and the current will still flow.
However, most superconducts can only conduct at very low temperatures up to -200 degrees Celcius. This is because, at that temperature, their atoms and molecules are relatively settled, hence they pose little or no resistance to the flow of current.
This as you can guess is extremely difficult to do, as you will need a lot of effort to cool it to that temperature and maintain it.
This makes option a the answer:
The cost of keeping the semiconductor below the critical temperature is unreasonable.
We getting addicted so it keeps us from getting bored
They may be changed because they may find evidence of some thing that will change their perspective on things.
The Nucleus contains Protons and Neutrons.
The Neutrons does not have a charge.
The Protons are positively charge.
Hence the charge on the Nucleus, would be the charge of the proton, which is positive.
Hence Nucleus is Positively Charged.
