can google answer all questions?

Not really. Google can't really answer any questions with absolute correctness. Google is just a tool that gathers information from other websites and presents them to you. Google does often give an answer to every question, but it doesn't mean it is correct. The correctness of an answer is what matters most. Sometimes, the search engine results will present the answer to you with more confidence and give you the answer without needing to click into a website. These are called featured snippets. This still isnt something that comes from the engine, it is information from other websites that google trusts to be fairly accurate.