Final answer:
A ruler is a tool shaped like an L and is commonly used for checking wall studs and sole plates to ensure right angles.
Step-by-step explanation:
The tool that is shaped like an L and is often used for checking wall studs and sole plates to ensure they have right angles is a ruler. A ruler is a straight edge tool typically marked with inches, centimeters, or millimeters, making it suitable for measuring objects in various units. It is used in carpentry, engineering, and other fields that require precise measurements. By aligning the ruler with the studs or sole plates, you can visually confirm if they are at right angles.