Calculate the volume of 0.1 M NaOH solution required to neutralise the products formed by dissolving 1.1 g of P4O6 in H2O.
Reaction of P4O6 in H2O is:
The reaction of Phosphorous acid with water is:
The above two reactions can be written in combined form:
1 mole of 
is neutralized by 8 moles of NaOH
of P4O6 will be neutralized by 
moles of NaOH
Molarity of NaOH solution is 0.1 M i.e. 0.1 mole is present in 1 L of water
So, 
moles of NaOH will be present in = 
The volume of 0.1 M NaOH required is 0.4 L or 400 mL.
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