Which of the following are examples of empty set ?
(i) Set of all even numbers divisible by 5.
(ii) Set of all even prime numbers.
(iii) {x:x2=0 and x is rational}.
(iv) {x : x is a natural number, x < 8 and simultaneously x > 12}.
(v) {x : x is a point common to any two parallel lines}.
Find, which of the following sets are empty:
(i)The set of points of intersection of two parallel lines.
(ii) A={x:x∈N and 5< x≤6}
(iii) B={x:x2+4=0,x∈N}
(iv)C={even numbers between 6&10}
(v) D={prime numbers between 7&11}
Note : The set, which has no element in it, is called the empty or null set.