Here are the mistakes and corrections for the sentences:

2. **Mistake:** "so she is"
**Correction:** "and she is"
**Revised Sentence:** "She is an intelligent student, and she is an active member of our club."

4. **Mistake:** "but" (this is an inappropriate conjunction here)
**Correction:** "and"
**Revised Sentence:** "Antony is a famous student in his school, and he is never arrogant."

5. **Mistake:** "watering the trees, or my grandmother is cooking."
**Correction:** "watering the trees, and my grandmother is cooking."
**Revised Sentence:** "My grandfather is watering the trees, and my grandmother is cooking."

6. **Mistake:** "didn’t" (should be in the past tense)
**Correction:** "practised hard for the competition, so he won the race."
**Revised Sentence:** "Jack practised hard for the competition, so he won the race."

8. **Mistake:** "but"
**Correction:** "or"
**Revised Sentence:** "We can eat out, or we can order some chicken from this app."

10. **Mistake:** "therefore" (can be simplified)
**Correction:** "so"
**Revised Sentence:** "You should do morning exercises regularly, so you can’t be in good shape."

Feel free to ask if you need more assistance!