It should be "Is a weapon a dangerous object?" or "Is this weapon a dangerous object?"
Hai! I think your first sentence is better than the latter. Also, the translation could be plural, "Are weapons dangerous objects?", with the same meaning. Please, try to report your sentence.
Selamat belajar! :)
I don't understand why Apa does not mean "what" . If it was "Adalah" I could understand the answer . What am I missing?