Cards, marked with numbers 5 to 50, are placed in a box and mixed thoroughly.

All possible outcomes are 5, 6, 7, 8...................50.

(i)  

Out of the given numbers, the prime numbers less than 10 are 5 and 7.
Let E1 be the event of getting a prime number less than 10.
Then, number of favourable outcomes =  2​   

$\therefore P$ (getting a prime number less than 10$)=\frac{2}{46}=\frac{1}{23}$

(ii)

Out of the given numbers, the perfect squares are 9, 16, 25, 36 and 49.  
Let E2 be the event of getting a perfect square.
Then, number of favourable outcomes = 5​    

$\therefore P$ (getting a perfect square) $=\frac{5}{46}$