2.30 p.m.
$\text{Let the distance between towns } P \text{ and } Q \text{ be } 275 \text{ km.}$
$\text{Speed of the first rider} = 25 \text{ km/hr}$
$\text{Speed of the second rider} = 20 \text{ km/hr}$
$\text{The first rider starts at } 8 \text{ a.m.}, \text{ and the second rider starts at } 9 \text{ a.m.}$
$\text{By the time the second rider starts, the first rider has traveled:}$
$ \text{Distance covered by first rider in 1 hour} = 25 \times 1 = 25 \text{ km} $
$\text{Remaining distance between them:}$
$ = 275 - 25 = 250 \text{ km} $
$\text{Relative speed when they move towards each other:}$
$ = 25 + 20 = 45 \text{ km/hr} $
$\text{Time taken to meet:}$
$ = \frac{250}{45} = \frac{50}{9} = 5.56 \text{ hours} $
$\text{Converting into hours and minutes:}$
$ 5.56 \text{ hours} = 5 \text{ hours } 33.6 \text{ minutes} $
$\text{The second rider started at } 9 \text{ a.m.}, \text{ so they will meet at:}$
$ 9 + 5 \text{ hours } 33.6 \text{ minutes} = 2:33 \text{ p.m.} $