On the following tap size 1/4 in. -20 UNC-2A, identify thread meaning for 2A? c. Coarse or Fine b. Number of threads per inch of length f. Internal d. Class of thread e. External a. Major diameter Question 4 On the following tap size 3/4 in. -10 UNC-2B, identify thread meaning for UNC? f. Internal b. Number of threads per inch of length e. External d. Class of thread a. Major diameter c. Coarse or Fine 10 pts

For the tap size \(1/4 \text{ in.}-20\) UNC-2A:<br /><br />- **2A** refers to the **Class of thread** (d). The "2" indicates a medium fit, and "A" denotes an external thread.<br /><br />For the tap size \(3/4 \text{ in.}-10\) UNC-2B:<br /><br />- **UNC** stands for **Unified National Coarse** (c), which indicates the thread series. It specifies that the threads are coarse rather than fine.<br /><br />These identifications help in understanding the specifications and applications of the threads in mechanical and engineering contexts.