Hướng dẫn:

${{n}_{PbO}}=\frac{{{m}_{PbO}}}{{{M}_{PbO}}}=\frac{22,3}{223}=0,1\left( mol \right)$

${{n}_{ZnO}}=\frac{{{m}_{ZnO}}}{{{M}_{ZnO}}}=\frac{12,15}{81}=0,15\left( mol \right)$

$2PbO+C\xrightarrow{{{t}^{0}}}2Pb+C{{O}_{2}}$                    (1)

0,1              0,1              (mol)

$2ZnO+C\xrightarrow{{{t}^{0}}}2Zn+C{{O}_{2}}$        (2)   
0,15            0,15            (mol)

Theo phương trình (1) có: ${{n}_{Pb}}={{n}_{PbO}}=0,1\left( mol \right)$

Theo phương trình (2) có: ${{n}_{Zn}}={{n}_{ZnO}}=0,15\left( mol \right)$

$\Rightarrow {{m}_{Pb}}={{n}_{Pb}}.{{M}_{Pb}}=0,1.207=20,7\left( g \right)$

${{m}_{Zn}}={{n}_{Zn}}.{{M}_{Zn}}=0,15.65=9,75\left( g \right)$

$\Rightarrow {{m}_{KL}}={{m}_{Pb}}+{{m}_{Zn}}=20,7+9,75=30,45\left( g \right)$

Chọn đáp án A