Hi Abdul,
It all depends on a number of things.
- Is this point to point 10G LAN?
- Will any FEC options be used.
- Will there be DCU's to compensate for any Chromatic Dispersion on the span.
Here is the spec sheet link.
http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/dwdm-transceiver-modules/data_sheet_c78-711186.html
As you can see with different options used(i.e. DCU's or FEC) you have different Rx sensitivity which will give you either less or more of an optical budget on your span.
Thanks,
Ryan