Question

Which of the following collections is not a set?

• A. All natural numbers which divide 42.
• B. The vowels in the English alphabet.
• C. Names of rivers in India.
• D. Names of 10 most renowned actors.

Answer 1

The correct option is D

Names of 10 most renowned actors.

A set is a well-defined collection of objects.

a) Vowels in English alphabet are a, e, i, o, u. So, this is a set.

b) All natural numbers that divide 42 are 1, 2, 3, 6, 7, 14, 21, 42. This is also a set.

c) The collection of most renowned actors is not well-defined, because the criterion for selecting an actor as most renowned may vary from one person to another. So, this is not a set.

d) We may not be able to recollect immediately the names of all rivers, but the collection is well-defined i.e., given a river name, we can say whether it belongs to this set or not.