Which (NON-QUESTION) – cuál
(Pronounced kwahl)
To remember that which (non-question) is pronounced kwahl (cual) in Spanish, use the following mnemonic:
She will choose the one which she loves the most, but both are equal (cuál) in looks and kindness.

Examples of cual (which) in a sentence
¿Cuál de estos libros prefieres?
(Which of these books do you prefer?)
No sé cuál camino es el correcto.
(I don't know which road is the correct one.)
¿Cuál de los dos prefieres? ¿el rojo o el azul?
(Which of the two do you prefer? The red or the blue?)