The mass of water decomposed to produce 50 g oxygen has been 56.28 g. Thus, option D is correct.
The reaction for the decomposition of water has been:

From the balanced equation, 2 moles of water decomposes to form 1 moles of hydrogen and 1 mole of oxygen.
The mass of oxygen produced has been 50 g. The moles of oxygen has been given by:

The moles of oxygen has been:

The moles of oxygen produced has been 1.5625 mol.
The moles of hydrogen decomposed has been given from the balanced chemical equation as:

The moles of hydrogen decomposes has been 3.125 mol.
The mass of hydrogen decomposed has been given by:

The mass of water decomposed to produce 50 g oxygen has been 56.28 g. Thus, option D is correct.
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