1.

Chief ore of `Zn` is `ZnS`. The ore is concentrated by froth flotation process and then heated in air to convert `ZnS` to `ZnO`. ltntgt `2 ZnS + 3O_(2) rarr 2 ZnO + 2 SO_(2)`…(i) `ZnO`, thus formed is treated with dilute `H_(2) SO_(4)`. `ZnO + H_(2) SO_(4) rarr ZnSO_(4) + H_(2) O` ....(ii) On electrolysis of `ZnSO_(4(aq)), Zn` metal is produced. `2 ZnSO_(4) + H_(2) O rarr 2 Zn + 2H_(2) SO_(4) + O_(2)`....(iii) How many kilomoles of `NaOH` are required to dissolve all the `ZnO` produced in reaction `(ii)` ?A. 1.16B. 2.32C. 4.64D. 9.28

Answer» Correct Answer - C
1 mol ZnS gives 1 mol of `ZnO`
`97 kg ZnS` gives `1` mol of `ZnO`
`225 kg ZnS -= (81)/(97) xx 225 kg ZnS = 187.88 kg ZnO`
=`(187.88)/(81) kg ZnO`
=`2.3195` k mol of `ZnO`
1 mol of `ZnO` dissolves in `2 mol` of `NaOH`
`2.3195` k mol of `ZnO` dissolves in
`2 xx 2.3195` k mol of `NaOH = 4.64` k mol of `NaOH`.


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