Pls tell me the answer of this question

Directions: count the number of atoms. ar co2 na3po4 so3 nac2h3o2

See the attachment and solve question 5th

Find an expression for the electric field e⃗ at the center of the semicircle. hint: a small piece of arc length δs spans a small angle δθ=δs /r, where r is the radius. express your answer in terms of the variables q, l, unit vectors i^, j^, and appropriate constants.