(i) The set of months of a year is a finite set because it has 12 elements.(ii) {1,2,3....} is an infinite set as it has infinite number of natural numbers.(iii) {1,2,3,...99,100} is a finite set because the numbers from 1 to 100 are finite in number.(iv) The set of positive integers greater than 100 is an infinite set because positive integers greater than 100 are infinite in number.(v) The set of prime numbers less than 99 is a finite set because prime numbers less than 99 are finite in number.