Three coins are tossed.
$\therefore$ The sample space =$2^3=8$ possible outcome
Let A be the event "Exactly one tail"
Let B be the event "Exactly two tail"
Let C be the event "Exactly three tails"
$\therefore A\cap B \cap C=\phi$ but $A\cup B \cup C\neq S$
$\therefore A,B$ and C are mutually exclusive but not exhaustive.