the front face in one direction

the front face in both directions

the inner face in one direction

the inner face in both directions

only (ii) is correct

(i) and (ii) are correct

(iii) and (iv) are correct

only (iv) is correct

not needed

provided equally on inner and front faces

provided more on inner face than on front face

provided more on front face than on inner face

top face perpendicular to wall

bottom face perpendicular to wall

both top and bottom faces perpendicular to wall

none of the above

(i) and (ii),

(ii) and (iii)

(i) and (iv)

(iii) and (iv)