Here are the answers for the questions you provided, focusing on the position of the primary stress:

1. **C. appliance** is the word that differs. The stress is on the second syllable (ap-PLI-ance).

2. **B. invention** is different as it has stress on the second syllable (in-VEN-tion).

3. **C. careless** is the one as it has stress on the first syllable (CARE-less).

4. **A. scientist** has stress on the first syllable (SCI-en-tist).

5. **D. carefully** has the stress on the first syllable (CARE-fully).

6. **C. usefulness** is different with stress on the first syllable (USE-fulness).

7. **B. hopeless** has stress on the first syllable (HOPE-less).

8. **A. excitement** differs with the stress on the second syllable (ex-CITE-ment).

9. **C. exciting** has stress on the second syllable (ex-CIT-ing).

10. **D. completed** has stress on the second syllable (com-PLE-ted).

11. **C. submitting** with stress on the second syllable (sub-MIT-ting).

12. **B. horrible** is the one that differs with stress on the first syllable (HOR-ible).

If there are specific items from the numbered list to further explore, or if you need clarification on any point, feel free to ask!