welcher / was

German Interrogative and Relative Pronouns: welcher and was

In German, welcher and was can change roles depending on whether you are asking a question or connecting clauses. Here is the breakdown of their specific functions.

1. welcher as an Interrogative Word (Which / Which one)

We use welcher to ask about a specific choice from a known group. It functions like an adjective and changes its ending to match the gender and case of the noun it describes.

• Masculine: Welcher Rock ist schöner? (Which skirt is prettier?)
• Feminine: Welche Tasche nimmst du? (Which bag are you taking?)
• Neuter: Welches Auto kaufst du? (Which car are you buying?)

2. was as an Interrogative Word (What)

We use was for general questions about things, activities, or ideas. It is indeclinable (its form does not change) and does not usually precede a noun directly.

• General Inquiry: Was ist das Problem? (What is the problem?)
• Actions: Was machst du heute Abend? (What are you doing tonight?)
• Abstract: Was hast du gestern gedacht? (What were you thinking yesterday?)

3. was as a Relative Pronoun (That / Which / What)

Unlike standard relative pronouns (der, die, das), was is used as a relative pronoun only in specific grammatical contexts. It introduces a subordinate clause where the verb goes to the end.

• After Neuter Indefinites: Use it after words like alles (everything), etwas (something), nichts (nothing), and vieles (much).
  Example: Das ist alles, was ich sagen kann. (That is everything [that] I can say.)
• After Superlatives: Use it after a neuter adjective used as a noun, especially in the superlative form.
  Example: Das Beste, was mir passiert ist. (The best thing that happened to me.)
• After the Demonstrative das:
  Example: Er gab mir das, was ich wollte. (He gave me what I wanted.)
• Referring to a Whole Clause: Use it when the relative pronoun refers to the entire previous statement rather than just one word.
  Example: Er kam zu spät, was mich sehr ärgerte. (He arrived late, which annoyed me a lot.)

Note: In German relative clauses, you can never omit the pronoun (unlike in English, where you can often leave out "that").