(i) Given: Set of odd natural numbers divisible by 2.

As we know set is a collection of well defined objects.

Let we represent the given set in roaster form:

⇒ Set of odd natural numbers divisible by 2 is {ϕ}.

Because no odd natural number can be divided by 2. Hence, it is a null set.

(ii) Given: Set of even prime numbers.

As we know set is a collection of well defined objects.

Let we represent the given set in roaster form:

⇒ Set of even prime numbers is {2}.

Because 2 is an even prime number. Hence, it is not a null set.

(iii) Given: {x : x is a natural numbers, x < 5 and x > 7}

As we know set is a collection of well defined objects.

Let we represent the given set in roaster form:

⇒ {x : x is a natural numbers, x < 5 and x > 7} is {ϕ}.

Because no number can be simultaneously less than 5 and greater than 7.Hence, it is a null set.

(iv) Given: {y : y is a point common to any two parallel lines}

As we know set is a collection of well defined objects.

Let we represent the given set in roaster form:

⇒ {y : y is a point common to any two parallel lines} is {ϕ}.

Because two parallel lines never meet at any of the point so they don’t have any common point. Hence, it is a null set.