\(\text{a) }m_K=\dfrac{156,4\cdot29,92}{100}=46,8\left(g\right)\\ \Rightarrow m_{Ba}=m_{h^2}-m_K=156,4-46,8=109,6\left(g\right)\)\(\text{b) }Pthh:2K+2H_2O\rightarrow2KOH+H_2\left(1\right)\\
Ba+2H_2O\rightarrow Ba\left(OH\right)_2+H_2\left(2\right)\)\(\text{
c) }n_K=\dfrac{m}{M}=\dfrac{46,8}{39}=1,2\left(mol\right)\\
n_{Ba}=\dfrac{m}{M}=\dfrac{109,6}{137}=0,8\left(mol\right)\)
Theo \(pthh\left(1\right):n_{H_2\left(1\right)}=\dfrac{1}{2}n_K=\dfrac{1}{2}\cdot1,2=0,6\left(mol\right)\)
Theo \(pthh\left(2\right):n_{H_2\left(2\right)}=n_{Ba}=0,7\left(mol\right)\)
\(\Rightarrow\Sigma n_{H_2}=0,6+0,7=1,3\left(mol\right)\\
\Rightarrow\Sigma V_{H_2}=\Sigma n_{H_2}\cdot22,4=1,3\cdot22,4=29,12\left(l\right)\)