Probability of x success in n Bernoulli trials is $P(X=x)=C(n,x)p^{x}q^{n-x}$
p=probability of spade drawn = $\frac{13}{52}=\frac{1}{4}$
q=probability of spade not drawn = $1- \frac{1}{4} = \frac{3}{4}$
i) P(all five cards are spade) = $P(X=5)=C(5,5)(\frac{1}{4})^{5}(\frac{3}{4})^{0} = \frac{1}{1024}$
ii) P(only 3 cards are spade) =$P(X=3)=C(5,3)(\frac{1}{4})^{3}(\frac{3}{4})^{2} = \frac{90}{1024}$
iii) P(none is spade) = $P(X=0)=C(5,0)(\frac{1}{4})^{0}(\frac{3}{4})^{5} = \frac{243}{1024}$