Write the following sets in roster form:

(i) the set of first five odd counting numbers

(ii) the set of all even natural numbers less than 101

(iii) {months of year whose names begin with a vowel}

(iv) {one digit natural numbers which are perfect squares}

(v) the set of multiples of 7 which lie between -20 and 25

(vi) {factors of 36}

(vii) {prime factors of 360}

(viii) the set of whole numbers which are multiples of 5

(ix) the set of all letters in the word 'CHENNAI'

(x) the set of all vowels in the word 'MUSSOORIE'

(xi) the set of all consonants in the word 'MATHEMATICS'

(i) The first five odd counting numbers are 1, 3, 5, 7 and 9.

The required set = {1, 3, 5, 7, 9}

(ii) The even natural numbers less than 101 are 2, 4, 6, ……, 100.

The required set = {2, 4, 6, ……, 100}

(iii) The months whose names begin with a vowel (a, e, i, o, u) are April, August and October.

The required set = {April, August, October}

(iv) The one digit natural numbers are 1, 2, 3, 4, 5, 6, 7, 8 and 9. Out of these, the perfect squares are 1, 4 and 9.

The required set = {1, 4, 9}

(v) The multiples of 7 are ……, -21, -14, -7, 0, 7, 14, 21, 28, …… The multiples of 7 lying between -20 and 25 are -14, -7, 0, 7, 14 and 21.

The required set = {-14, -7, 0, 7, 14, 21}

(vi) The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18 and 36.

The required set = {1, 2, 3, 4, 6, 9, 12, 18, 36}

(vii) 360 = 2 × 2 × 2 × 3 × 3 × 5 = 2³ × 3² × 5

So, the prime factors of 360 are 2, 3 and 5.

The required set = {2, 3, 5}

(viii) The whole numbers which are multiples of 5 are 0, 5, 10, 15, 20, ……

The required set = {0, 5, 10, 15, 20, ……}

(ix) The letters in the word 'CHENNAI' are C, H, E, N, N, A, I. Writing each element only once, we get C, H, E, N, A, I.

The required set = {C, H, E, N, A, I}

(x) The vowels in the word 'MUSSOORIE' are U, O, O, I, E. Writing each element only once, we get U, O, I, E.

The required set = {U, O, I, E}

(xi) The letters in the word 'MATHEMATICS' are M, A, T, H, E, M, A, T, I, C, S. The consonants among these are M, T, H, M, T, C, S. Writing each element only once, we get M, T, H, C, S.

The required set = {M, T, H, C, S}