Answer
(a) $P(H)=1$
(b) $P(T)=0$
Work Step by Step
The sample set is $S=${$H$}, therefore the total number of outcomes is 1.
The probalitity of an event can be calculated as:
$P(A)=\frac{\text{favorable outcomes out of the sample set}}{\text{total number of possible outcomes}}$
This means, that the probability of the event that the toss is heads is 1, as there is one favorable outcome out of the sample set:
$P(H)=\frac{1}{1}=1$
The probability of the event that the toss is tails is 0, as there isn't any favorable outcome out of the sample set:
$P(T)=\frac{0}{1}=0$
