Revise the sentences below in which "who" or "whom" is used incorrectly. Then, indicate how "who" or "whom" is used in each sentence.

1. To play Kick the Can, the group must make a decision about whom will be counting.
2. Everyone else must hide from the person who is counting.
3. It was Tom who we caught hiding behind the car.
4. Tara was the one from whom he was running.
5. We know whom will count next.
6. The boy who was hiding behind the tree kicked the can.
7. Who did he chase?
8. I wasn't the one to whom he called out.
9. Is Helen the one whom was chosen to be the counter?
10. Now we've lost track of whom goes next.

My answers:
1. To play Kick the Can, the group must make a decision about who will be counting. (subject).
2. Everyone else must hide from the person who is counting. (subject).
3. We caught Tom who was hiding behind the car. (subject).
4. Tara was the one from whom he was running. (object of preposition).
5. We know who will count next time. (subject).
6. The buy who was hiding behind the tree kicked the can. (subject).
7. Whom he did chase? (direct object).
8. ?
9. ?
10. ?

Reread number 3.

8. to whom or to who?

9. who or whom was chosen?

10. of who or of whom?

The others are correct.

1-7 are correct.

I'm bolding the parts of the other three to help you focus.

8. I wasn't the one to whom he called out.

9. Is Helen the one whom was chosen to be the counter?

10. Now we've lost track of whom goes next.

3. We caught Tom who was hiding behind the car. (subject).

8. ?
9. Is Helen the one who was chosen to be the counter? (subject).
10. Noe we've lost track of who goes next. (subject).

Are my answers correct?

Please read 3 more carefully.

3. It was Tom who we caught hiding behind the car.

3. It was Tom whom we caught hiding behind the car.

Since your directions say "Revise..." I figured your first correction for #3 was correct. So now you have two correct versions of #3 to choose from!

"to whom" = what kind of phrase? (for #8)

8. I wasn't the one to who he called out.

"to whom" is correct because in this sentence "to" is a preposition. What is "whom" then?

An object of preposition?