The pair that on reaction will not evolve H2 gas is  

1.  Copper and HCl (aqueous)
2.  Iron and steam
3.  Iron and H2SO4 (aqueous)
4.  Sodium and ethyl alcohol

Subtopic:  Preparation & Properties |
 55%
From NCERT
AIPMT - 1998
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 H2Oon oxidation gives:

1. O-2

2. OH-

3. O2-

4. O2

Subtopic:  H2O2 (Hydrogen Peroxide) |
 58%
From NCERT
AIPMT - 1999
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Pure water can be obtained from sea water by:

1.  Centrifugation
2.  Plasmolysis
3.  Reverse osmosis
4.  Sedimentation

Subtopic:  Water |
 77%
From NCERT
AIPMT - 2001
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