Which one is correct ?
- "I don't know what was that"
or
- "I don't know what that was"
Which one is correct ?
- "I don't know what was that"
or
- "I don't know what that was"
The second sentence is the correct word order. You may hear the first sentence spoken in conversation but it will be punctuated like "I don't know. What was that?"
The correct answer, as Pavja2 said, is the second one. It's called an "indirect question". They aren't normal questions because they have the same word order as statements.
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