In which of the following reactions,standard reaction entropy change`(DeltaS^(@))`is positive and standard Gibb,s energy change`(DeltaG^(@))`decreases sharply with increasing temperature?A. `Mg(s)+(1)/(2)O_(2)(g)rarrMgO(s)`B. `(1)/(2)C("graphite")+(1)/(2)O_(2)(g)rarr(1)/(2)CO_(2)(g)`C. `C("graphite")+(1)/(2)O_(2)(g)rarrCO(g)`D. `CO(g)+(1)/(2)O_(2)(g)rarrCO_(2)(g)`

In which of the following reactions,standard reaction entropy change`(

1.	In which of the following reactions,standard reaction entropy change`(DeltaS^(@))`is positive and standard Gibb,s energy change`(DeltaG^(@))`decreases sharply with increasing temperature?A. `Mg(s)+(1)/(2)O_(2)(g)rarrMgO(s)`B. `(1)/(2)C("graphite")+(1)/(2)O_(2)(g)rarr(1)/(2)CO_(2)(g)`C. `C("graphite")+(1)/(2)O_(2)(g)rarrCO(g)`D. `CO(g)+(1)/(2)O_(2)(g)rarrCO_(2)(g)`
Answer» Correct Answer - A `C(s)+(1)/(2)O_(2)(g)rarrCO(g),Deltan+(1)/(2)` . Also the moles of gases increase and therefore entropy change `(DeltaS)` is positive. An increase in temperature will causes more change in `TDeltaS` . Also it is a combustion reaction and thus `DeltaH=-ve` Since `DeltaG=DeltaH-TDeltaS` `=-ve-(+ve)=-ve`

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