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Answer:
The new pressure is 44.4 kPa.
Explanation:
We have,
Initial volume, 
Initial pressure, 
It is required to find the new pressure when the volume is increased to 50 ml. The relationship between pressure and volume is known as Boyle's law.

is final pressure

So, new pressure is 44.4 kPa.
Dehydration is removal of water.
In alcohols dehydration is α-β elimination or 1,2 elimination, it means the hydroxyl group will be removed from α-carbon while the hydrogen will be removed from near by carbon.
In case of neopentyl alcohol there is no β hydrogen present on the β carbon [as shown in figure].
The only possible way for it to undergo dehydration is by rearrangement.
The process or mechanism can be understood as:
so the chief product is 2-methylbut-2-ene