Equation of plane passing through the point having position vector $\bar{a}$ and normal to $\overline{\mathrm{n}}$ is
$\therefore \overline{\mathrm{r}} \cdot \overline{\mathrm{n}} \cdot(2 \hat{\mathrm{i}}+3 \hat{\mathrm{j}}-4 \hat{\mathrm{k}})=(\hat{\mathrm{i}}-\hat{\mathrm{j}}+\hat{\mathrm{k}}) \cdot(2 \hat{\mathrm{i}}+3 \hat{\mathrm{j}}-4 \hat{\mathrm{k}})=2-3-4=-5$