Answer:
a) 4 N/C
b) 6.4×10^{-19} N
Explanation:
Since, the magnitude of charge is not given i am assuming it to be as 5 nC positive.
therefore, magnitude of electric field: E = F/q = 20/5 = 4 N/C
direction: downward
b) F = q E = 1.6 e^{-19}×4 = 6.4×10^{-19} N
upward