Final answer:
The angle between the scratches on the surface of the square will decrease as the square is heated uniformly.
Step-by-step explanation:
The angle between the scratches on the surface of the square will decrease as the square is heated uniformly.
When the square is heated, it will expand and become larger in size. As a result, the scratches on the surface of the square will move further apart, causing the angle between them to decrease.
This change in angle between the scratches is independent of whether theta is obtuse or acute.