The answer for the following question is given as postorder...
Q)One can convert a binary tree into its mirror image by traversing it in
Can anyone plz let me know the explanation

*This could be completely wrong I haven't used binary trees before*

Sounds to me like you convert to non-binary reverse then convert back to binary.

Have you read up about tree traversal?

Tree traversal
http://en.wikipedia.org/wiki/Tree_traversal

Post-order
http://en.wikipedia.org/wiki/Tree_traversal#Post-order

And there are even video on youtube.com, e.g.

Post order Traversal
http://www.youtube.com/watch?v=uv0qET0QyWc

Andy