So we have 10 runners of which Neeraj is 1
So a simple upper bound is 9
Think of a typical 400m footrace and how the inner lanes start further back - because they run a shorter route on the bends - so the inside lane starts "behind"
If Neeraj starts in last (the inside lane) and runs quicker than everyone but Ishant (who must have started 9th)
Then he would finish 2nd.
The answer is 9
And to answer about how long he could have been in second place
Neeraj started behind Ishant and at no point overtakes him - meaning he did not overtake Karan before Ishant did - thus the soonest he could have done so is 1:21 - meaning 9 seconds between then and completion
9 seconds assuming Ishant and Neeraj overtook karan simultaneously (negligible time difference between them)
A little caveat
if Neeraj starts infront of Ishant and we assume that Ishant overtakes Neeraj as the pair overtake Karan - then Neeraj is in second from 1:13 onwards - a total of 17 seconds
17 seconds if Neeraj starts infront of Ishant