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632 g of sodium thiosulphate `(Na_2S_2O_3)` reacts with copper sulphate to form cupric thiosulphate which is reduced sodium thiosulphate to give cupros compound which is dissolved in excess of sodium thiosulphate to form a complex compound sodium cuprothiosulphate `(Na_4[Cu_6(S_2O_3)_5])`. `CuSO_4+Na_2S_2O_3toCuS_2O_3+Na_2SO_4` `2CuS_2O_3+Na_2S_2O_3toCu_2S_2O_3+Na_2S_4O_6` `3Cu_2S_2O_3+2Na_2S_2O_3to underset("Sodium cuprothiosulphate")(Na_4[Cu_6(S_2O_3)_5])` In this process, 0.2 moles of sodium cuprothiosulphate is formed. `(O=16, Na=23, S=32)` The average oxidation states of sulphur in `Na_2S_2O_3 and Na_2S_4O_6` are respectively.A. `+5 & +2`B. `+2 & +2.5`C. `+5 & 2.5`D. `+2 & +4` |
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Answer» Correct Answer - B Suppose oxidation number of sulphur in `Na_2S_2O_3` is x `2+2x+3(-2)=0` or 2x=6-2 or 2x=4 x=+2 Suppose oxidation number of sulphur in `Na_2S_4O_6` is y 2+4y+3(-2)=0 or 4y =12-2 or 4y=10 y=+2.5 |
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