Doubt from ionic equilibrium

ionic-equilibrium
solved
moderate
finding-ph
pp
#1

#2

Is it option B?

#3

Sorry but I am getting -ve sign between them. There is some error.

#4

ans is D

#5

We both made a silly mistake.concentration the formate ion has concentration of (0.06*2/2) =0.06

#6

Ya I got it. When I look at the basic procedure of that formula I realise that.