The Delta G deg for 2C + O2 -> 2CO is -221 - 0.179 T kJ per mole of O2. At 1000 K the values of Delta G deg (kJ per mole of O2) for formation of some oxides are: MgO -1020; Al2O3 -1053; Cr2O3 -600; Cu2O -240. Which oxide can be reduced by carbon at 1000 K?

JEE Main levelSingle correct optionDifficulty 2 of 3mt206

The $Δ G^{\circ}$ for $2 C + O X_{2} 2 CO$ is $- 221 - 0.179 T$ kJ per mole of $O X_{2}$ . At 1000 K the values of $Δ G^{\circ}$ (kJ per mole of $O X_{2}$ ) for formation of some oxides are: $MgO$ $- 1020$ ; $Al X_{2} O X_{3}$ $- 1053$ ; $Cr X_{2} O X_{3}$ $- 600$ ; $Cu X_{2} O$ $- 240$ . Which oxide can be reduced by carbon at 1000 K?

At 1000 K the carbon line is at

- 221 - 0.179 \times 1000 = - 400

kJ. Carbon reduces an oxide only if the oxide line lies above this. Only

Cu X_{2} O

(

- 240

) is above

- 400

; the other three lie below.