**Answer:**

Total numbers of discs = 50

(i) Total numbers of favourable events = 81

Probability that it bears a two-digit number = 81/90 = 9/10

(ii) Perfect square numbers = 1, 4, 9, 16, 25, 36, 49, 64 and 81

Favourable numbers of events = 9

Probability of getting a perfect square number = 9/90 = 1/10

(iii) Numbers which are divisible by 5 = 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85 and 90

Favourable numbers of events = 18

Probability of getting a number divisible by 5 = 18/90 = 1/5