ANSWER:
6.1. ELEMENTS: Oxygen and 2 hydrogen. Oxygen is a non-metal. Hydrogen is a non-metal. So, there are no metals but two non-metal elements
6.2. ELEMENTS: Nitrogen and 3 hydrogens. Nitrogen is a non-metal. Hydrogen is also a non-metals. So, there are no metals but two non-metal elements.
6.3. ELEMENTS: Magnesium and oxygen. Magnesium is a metal. Oxygen is a non-metal. So, there is one metal and one non-metal.
I hope this helped :D