List the elements of the following set :

{x : x ∈ Z and x² ≤ 4}

List the elements of the following set :

{x : 3x - 2 ≤ 10 and x ∈ N}

Find which of the following sets are singleton sets :

(i) The set of points of intersection of two non-parallel straight lines on the same plane.

(ii) A = {x : 7x - 3 = 11}

(iii) B = {y : 2y + 1 < 3 and y ∈ W}