AP EAMCET Engineering 2013 Solved Paper

As a mixture of NH4OH and NH4Cl acts as a basic buffer, so its pH must be basic, (i.e., greater than 7), hence the answer must be 2 nd. It can also be find by calculations:
pOH=pKb+log‌

[salt]

[base ]

=4.8+log‌

0.2M

0.02M

=4.8×log‌10
pOH=4.8+1=5.8
∴ pH=14−pOH =14−5.8=8.2