Final answer:
The angle between two vectors with magnitudes of 8 and 5 units and a scalar product of zero is 90°, indicating they are orthogonal to each other.
Step-by-step explanation:
If the magnitude of two vectors is 8 units and 5 units, and their scalar product is zero, the angle between the two vectors is 90°. The scalar product, also known as the dot product, of two vectors can be expressed as A ⋅ B = |A||B|cos(θ), where |A| and |B| are the magnitudes of the vectors and θ is the angle between them. When the scalar product is zero, this implies that cos(θ) is zero, which occurs only when θ is 90°, meaning the vectors are orthogonal to each other. This is consistent with the orthogonal nature of unit vectors along the axes in the Cartesian coordinate system. Hence, the answer to the question is option (4) 90°.