Spanish: Accent Marks On Question Words In A Statement
Should the following question words have accent marks in a statement like "I don't know WHO bought the horse." or do they drop their accents?

Yo no se... (I don't know...)

1. quién / quien se compró el caballo. = who bought the horse.

2. qué / que ella se compró. = what she bought.

3. dónde / donde ella se compró el caballo. = where she bought the horse.

4. cuándo / cuando ella se compró el caballo. = when she bought the horse.

5. por qué / por que ella se compró el caballo. = why she bought the horse.

6. cómo / como ella se compró el caballo. = how she bought the horse.

7. cuántos / cuantos caballos ella se compró. = how many horses she bought.I meant to not include "se" in the sentences. Ugh. :)

Question

Spanish: Accent Marks On Question Words In A Statement
Should the following question words have accent marks in a statement like "I don't know WHO bought the horse." or do they drop their accents?

Yo no se... (I don't know...)

1. quién / quien se compró el caballo. = who bought the horse.

2. qué / que ella se compró. = what she bought.

3. dónde / donde ella se compró el caballo. = where she bought the horse.

4. cuándo / cuando ella se compró el caballo. = when she bought the horse.

5. por qué / por que ella se compró el caballo. = why she bought the horse.

6. cómo / como ella se compró el caballo. = how she bought the horse.

7. cuántos / cuantos caballos ella se compró. = how many horses she bought.I meant to not include "se" in the sentences. Ugh. :)

Answer

If grammar is not your strong point, pay attention to this tip: If the word is accentuated there is a gap in the pronunciation. If it is not, there is not.
Comoella se compró un caballo, yo me compré un perro. Asshe bought a horse, I bought a dog. NOTE THAT THERE IS NO GAP BETWEEN COMO AND ELLA. 
No entiendo cómo  ella se compró un caballo. I don´t understand how  she bought a horse. NOTE THAT THERE IS A GAP BETWEEN COMO AND ELLA. Also the pronunciation of “Cómo” and “How” is stressed. 
This is also a good tip also for Spanish speaking people.

Answer

Las preguntas llevan acentos. También es muy importante los signos de interrogación ¿?
¿Qué?
¿Quién?
¿Cómo?
¿Cuándo? 
¿Dónde?
¿Por qué?
¿Para qué?

Answer

all of them Shawn :) If you can transform the affirmative into a question..then they should have the accent