Use delta ( + or - ) to show direction of expected polarity?

Question

for each of the bonds indicated.

do you use electronegative numbers? how? I know the answers (i have the book) i just want to know how im supposed to know it for a test.

a) H3C - CL

b) H3C - NH2

c) H2N - H

d) H3C - SH

e) H3C - MgBr

f) H3C - F

Answer 1

Yes, use electronegativities.
Cl is -, C is +.
The more EN element will be -, the less EN element will be +.