Which one is correct? “Explain what this is?” or “Explain what is this?”

• Please explain what is this?
  or
• Please explain what this is?

Which one is grammatically correct?

Answer

Your sentence, despite ending with a question mark (a period would be more correct), is an imperative sentence: “(You) please explain…”

Therefore, the noun comes before the verb and you say “Please explain what this is.”

Attribution
Source : Link , Question Author : mayday445 , Answer Author : PlutoThePlanet