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Thermodynamics question

2003 · Q117
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Thermodynamics question

2003 · Q117

NEETChemistryThermodynamicsMCQ+4 / −1
For which one of the following equations is Δ\DeltaΔHoreact equal to Δ\DeltaΔHof for the product ?
  1. A
    Xe(g) + 2F2(g) →\to→ XeF4(g)
  2. B
    2CO(g) + O2(g) →\to→ 2CO2(g)
  3. C
    N2(g) + O3(g) →\to→ N2O3(g)
  4. D
    CH4(g) + 2Cl2(g) →\to→ CH2Cl2(l) + 2HCl(g)
View written solutionFree

Correct answer: A

Heat of formation, Δ\Delta ΔHof of a substance is the amount of heat absorbed or released when one mole of this substance is formed directly from its constituent elements.

In option (a), one mole of XeF4 is formed from its constituent elements i.e., Xe and F2 thus, the equation has equal value of Δ\Delta ΔHor and Δ\Delta ΔHof .

In option (b), the constituent atoms should be carbon and oxygen only but the reactant used is CO thus,

Δ\Delta ΔHor ≠\ne= Δ\Delta ΔHof

In option (c), the reactant used is O3 which is again not in its element form thus,

Δ\Delta ΔHor ≠\ne= Δ\Delta ΔHof

In option (d), two products are formed thus

Δ\Delta ΔHor ≠\ne= Δ\Delta ΔHof

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