I would say Na. Oxygen has 2 valence electrons and when reacting with other molecules, the ones with the fullest or emptiest shells will react the least. Both H2 and Na are in the Alkali Metals in the first row, but since H2 has 2 molecules, it would use more oxygen than Ana
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Answer : 
is the molecule that exhibit dipole-dipole forces as its strongest intermolecular force.
Explanation : The shape or geometry of given molecules of 
, 
, 
, 
and are linear, linear, tetrahedral, trigonal planar and angular respectively.
The given molecules , , , are symmetrical molecules. These symmetric molecules cannot exists as dipole even they contain polar bonds. Thus, these molecules will not exhibit dipole-dipole forces.
molecule has polar bonds and unsymmetrical bonds as shown in attached image. This molecule cannot exhibit H-bonding. It exhibit only dipole-dipole forces.
Therefore, molecule exhibit dipole-dipole forces as strongest intermolecular force.
The answer is ( 2.6 mol HCl )
