land exchange

I think 1 crore will be considered as his full sale consideration and mr.A has to calculate its capital gain.

tax treatment in the hands of mr.B???

l think mr.B has capital loss.
bcoz.mr.B got land of 5900000 inexchange of land worth ₹1 cr.
here both are selling the land and purchasing the another land at the same time.

The first step in how to calculate long-term capital gains tax is generally to find the difference between what you paid for your property and how much you sold it for—adjusting for commissions or fees. Depending on your income level, your capital gain will be taxed federally at either 0%, 15% or 20%.