NCERT Exercise 1.2 Q1 - Sets
Question: Which are examples of the null set: (i) odd natural numbers divisible by 2; (ii) even prime numbers; (iii) {x : x is a natural number, x 7}; (iv) {y : y is a point common to any two parallel lines}?
Answer: (i), (iii), and (iv) are null sets; (ii) = {2}, so it is not a null set.
Full step-by-step NCERT solution with diagrams on Something by Zero.