For inorganic molecules, is ionic or covalent bonding more common?
Ionic is far more common. Except in the air. 79% of the air is N2 (covalent), 20% is O2 (covalent.)
This answer is about as vague as the question was.
Sodium sulfate - does it contain ionic, or covalent bonds?
I was thinking in the earth, ionic is far more common. Silicon dioxide- ionic. Iron, aluminum, carbon, magnesium, calcium, oxide (dioxide). And I have a quick question- in a hydroxide, are the O and the H ionic or covalently bonded to each other?
In your specific example they contain both bonds.
The question was clear and well answered.
Separate names with a comma.