Complex sentence: He most notably arranged the music to "Mer Hayrenik", the Armenian national anthem, as well as to a famous traditional Armenian lullaby "Oror Im Palas" (in Armenian Օրօր Իմ Բալաս).
Split into simpler sentences: He most notably composed the music to "Mer Hayrenik", the Armenian national anthem. He also made the arrangement of a famous traditional Armenian lullaby "Oror Im Palas" (in Armenian Օրօր Իմ Բալաս).