Combination # 1 - Hydrogen and Oxygen
Hydrogen combines with Oxygen  to form H2O

Combination # 2 - Helium and Einsteinium
Helium doesn't combine with Einsteinium
One or more elements is a noble gas.
One or more elements is man made.


Combination # 3 - Manganese and Fluorine
Manganese doesn't combine with Fluorine
Would require more than 4 atoms to balance.


Combination # 4 - Silicon and Hydrogen
Silicon combines with Hydrogen  to form H4Si

Combination # 5 - Copernicium and Nitrogen
Copernicium doesn't combine with Nitrogen
Both valence charges have the same polarity.
One or more elements is man made.


Combination # 6 - Gold and Carbon
Gold combines with Carbon  to form C3Au2


Combination # 7 - Boron and Carbon
Boron combines with Carbon  to form C3B4