Class 11

Math

Co-ordinate Geometry

Sets

Which of the following are examples of the null set?

(i) Set of odd natural numbers divisible by $2$

(ii) Set of even prime numbers

(iii)

(ii) $A={2}$.

A set of even prime numbers is not a null set because $2$ is an even prime number.

(iii) ${x:xis a natural number,x<5and x>7}$ is a null set because a number cannot be simultaneously less than $5$ and greater than $7$.

(iv) ${y:yis a point common to any two parallel lines}$ is a null set because parallel lines do not intersect. Hence, they have no common point.