Step 1: The unit vector perpendicular to a plane is given by the cross product of two vectors lying on the plane. Step 2: Using the given points, we form two vectors and compute their cross product. After normalizing the result, we get \( \frac{1}{\sqrt{5}} (5\hat{i} - \hat{j} - 7\hat{k}) \).
Final Answer:
\[
\boxed{\frac{1}{\sqrt{5}} (5\hat{i} - \hat{j} - 7\hat{k})}
\]