Learn Spanish (Latin America): ¿Cuál es el problema?

When asking "What is [something]?", Spanish almost always uses ¿Cuál es...? instead of ¿Qué es...?. You use qué to ask for a definition or explanation (like "What is a black hole?"), but you use cuál (which literally means "which") when asking to identify a specific thing out of many possibilities, like a problem, your name, or your phone number.

Why is it el problema? Doesn't the "-a" ending usually make a word feminine?

Normally, yes! But problema is a famous exception. Many Spanish words ending in "-ma" that were borrowed from Greek are actually masculine. You just need to memorize el problema, along with other common exceptions like el sistema (the system) and el idioma (the language).

Does cuál change if we are talking about more than one problem?

Yes! While cuál stays exactly the same for masculine and feminine words, it does change for plurals. If you wanted to ask "What are the problems?", you would use the plural form cuáles and say ¿Cuáles son los problemas?.