Answer:
Part a)

Part b)

Explanation:
As we know that capacitor plate is connected across 2.1 V and after charging it is disconnected from the battery
So here we can say that charge on the plates will remain conserved
So we will have

now dielectric is removed between the plates of capacitor
so new potential difference between the plates




Part b)
Now the capacitor plates are again isolated and unknown dielectric is inserted between the plates
So again charge is same so potential difference is given as




Its because particles of air inside it are moving faster and making more pressure plus there is a pressure from the street.
Answer:



Explanation:
From the question we are told that
Electric field of intensity 
Rectangle parameter Width
Length 
Angle to the normal 
Generally the equation for Electric flux at parallel to the yz plane
is mathematically given by



Generally the equation for Electric flux at parallel to xy plane
is mathematically given by



Generally the equation for Electric flux at angle 30 to x plane
is mathematically given by




B, the surface of a flat table.