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VikaD [51]
3 years ago
6

Which of the following is a chemical change?

Physics
1 answer:
klemol [59]3 years ago
3 0

a). Water is still H₂O after it freezes.

b). Ice is still H₂O after it melts.

c). Wire is still Cu when it's bent.

d). Paper combines with the O₂ in the air, and turns into
     a lot of new compounds when it burns.

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qwelly [4]

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The alternative to nuclear fission reactors in a nuclear fusion reactor. Explain why it is much more difficult to get a fusion r
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Answer: The major challenges are as

1) understanding of the plasma: Plasma is a soup like mixture of subatomic particles of different atoms nuclei and electrons that are shattered apart by the temperature at which plasma is formed. further research is needed to understand the behavior of plasma so that it can be put to a proper use.

2) Confinement of plasma: Once we get the plasma we need to hold it so that we can obtain heat from it to drive a steam turbine but the sheer temperature of plasma is in millions of Celsius thus currently making it impossible to confine conventionally. Scientists use a loop of electric and magnetic fields to keep it in circulatory like manner so that it can be studied.

3) finally to obtain electricity from the plasma it should be stable to produce electricity. But currently to obtain pressure, temperature so that we have a sustained supply is highly difficult in technical and economical aspects.

Inertial confinement: In order to get the nuclei of atoms close enough for fusion this type of method used compression of the nuclei into highly small volumes.This is accomplished by use of lasers which are directed towards the fuel pellets that implode and travel towards other nuclei making fusion possible. It's main advantage is that it requires lesser time to initiate fusion but the disadvantage being that a large power is used to fire the lasers and the lasers should all hit the small target.

Magnetic Confinement: In this method we use a magnetic and electric fields in a properly designed space to keep the plasma in motion. In motion the nuclei of the atoms come close enough to initiate fusion.It's advantage being less power is required to start the process as compared to inertial confinement and the disadvantage being that plasma confinement is currently not properly understood.

5 0
3 years ago
Help! 50 points each and brainliest!!!
klio [65]

Answer:

Your answer is the following...

(b)"Many valence electrons are shared between the atoms"

Explanation:

7 0
2 years ago
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A repeating disturbance that transfers energy through matter or space is called a _____.
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Collateral Damage

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3 years ago
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The current in an electric hair dryer is 10
Vikki [24]
First let's convert the time in seconds:
\Delta t= 5 min= 5 min \cdot (60 s/min)= 300 s

The current is defined as the quantity of charge flowing through a certain section of a circuit per unit of time:
I= \frac{Q}{\Delta t}
Using I=10 A, and \Delta t=300 s, we can find the amount of charge flown through the hair dryer in this time:
Q=I \Delta t=(10 A)(300 s)=3000 C

The charge of a single electron is q=1.6 \cdot 10^{-19} C, so the number of electrons flown through the hair dryer is the total charge divided by the charge of a single electron:
N= \frac{Q}{q}= \frac{3000 C}{1.6 \cdot 10^{-19} C} =1.88 \cdot 10^{22}
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