Question

Calculate the pH at the equivalence point in titrating 0.110 M solution of sodium hydrogen chromate (NaHCrO4) with 8.0×10−2 M NaOH.

Answer 1

You need to know what volume is being titrated. I will call (concn of salt as y) and that will be mole of salt/total volume, whatever that is (total volume is volume of starting NaHCrO4 + volume of NaOH added).
.......CrO4^2- + HOH ==> HCrO4^- + OH^-
init....y...................0......0
change..-x..................x......x
equil.. y-x.................x.......x

Kb for CrO4^2- = (Kw/K2 for H2CrO4) = (HCrO4^-)(OH^-)/(CrO4^2-)
Substitute and solve for x = (OH^-) and convert to pH.

Answer 2

2.3