relation between potential difference and electric field is given as

so here we know that
d = 3 cm



So now when plates are separated to 4 cm distance carefully
the potential difference between them will change but the electric field between them will remain constant
So at distance of 4 cm also the electric field will be E = 1000 N/C
The data convincingly show that wave frequency does not affect wave speed. An increase in wave frequency caused a decrease in wavelength while the wave speed remained constant. The last three trials involved the same procedure with a different rope tension.
A-11 polar easterlies
b-8 winds blowing between the equator and 30° N and south
c-10
d-9
C.
Explanation: ionic compounds are metals and nonmetals, refer to your periodic table