Which of the following are sets? Justify your answer.

Which of the following are sets? Justify your answer. 

(i) The collection of all months of a year beginning with the letter J. 

(ii) The collection of ten most talented writers of India. 

(iii) A team of eleven best-cricket batsmen of the world. 

(iv) The collection of all boys in your class. 

(v) The collection of all natural numbers less than 100. 

(vi) A collection of novels written by the writer Munshi Prem Chand. 

(vii) The collection of all even integers. 

(viii) The collection of questions in this Chapter. 

(ix) A collection of most dangerous animals of the world.