Question

11. Which of the following is a null ( or empty) set?
(A) { x:x is a natural number and x2 + 1 = 10 }
(B) { x:x is a natural number and x2 = 121 }
(C) { x:x is a natural number and x2 = – 10 }
(D) { x:x is a natural number and x2 ≤ 100 }

Answer 1

Answer

Empty set is a set which does not contains any element.

i] Set of all even natural numbers divisible by 5

→ Not a Empty set, e.q. 10, seven natural number &

divisible by 5.

ii] Set of all even prime number

→ not a Empty set e.q. 2 is even prime number

iii] {x:x2−2=0 & x is rational  }

→ not a Empty set, e.q. x=2 satisfy which is a

rational number.

iv] {x:x is a natural number x < 8 & x > 12  }

→ It is a empty set because if a natural number is less

than 8, then it cannot be greater than 12.

v] {x:x is a point common to any two parallel lines }

→ A empty set because there will be no common

point between two parallel lins.

So (iv) & (v) are examples of empty of empty sets.

Refer the attachment