<u>Answer:</u> The correct option is
<u>Explanation:</u>
A catalyst is defined as the chemical species that increases the reaction rate but does not participate in it and is left behind after the completion.
A homogeneous catalyst is one that is present in the same phase as the reactants and products.
A heterogeneous catalyst is one that is present in different phase as that of reactants and products.
For the given chemical reaction:

As all the reactants and products are in gaseous state so, the homogeneous catalyst must also be in the gaseous state only.
Hence, the correct option is 
The simplified model of the hall effect proved that the current (electric) in metals are carried by electrons and not protons. The hall effect introduced the hall coefficient which is the ratio of the induced electric field to the current density x applied magnetic field. This coefficient is unique for each type of metal.
Answer:
D. Crystallization
Explanation:
Let's clarify the irrelevant terms first.
- unification: This term has nothing to do with chemistry at all
- lithification: When the problem mentions magma and lava, you might think that this term is related to the process here. However, 'lithification' <em>do </em>have a precise meaning in geology. It refers to the process where sediments collapses into one single rock under pressure, which has nothing to do with the process mentioned here.
Now, for 2 terms that might confuse you: 'solidification' and 'crystallization' these also has precise scientific definition
Solidification is defined the process where substances in <em>liquid</em> phase changes its phase to <em>solid</em>. On first glance, this answer might seems correct, and yes, it is correct for this question. But not the <em>most</em> correct.
The keyword here is
'the internal components will arrange its self in an organized pattern.'
Crystallization is a special case of Solidification where the atoms or molecules of liquid solidify by spontaneously arrange themselves in periodic, ordered, and organized pattern. It might or might not happen during solidification depending on cooling rate, viscosity of liquid, and other factors.
So, Crystallization is the most correct answer here.
Answer:
1 a person sings into a microphone
2 the sound is converted into an electrical signal
3 the analog signal is converted into a digital signal made of many samples of the digital sound
4 the samples of the sound is converted into 1s and 0s
5 the digital pattern is converted to a medium such as a hard disk or flash drive
Explanation: