JEE Main · 2020 · Shift-IeasyTHERMO-122

If enthalpy of atomization for Br2(l) is x\,kJ/mol and bond enthalpy for Br2 is y\,kJ/mol, the relation between them:

Thermodynamics · Class 11 · JEE Main Previous Year Question

Question

If enthalpy of atomization for Br2(l)\text{Br}_2(l) is x kJ/molx\,\text{kJ/mol} and bond enthalpy for Br2\text{Br}_2 is y kJ/moly\,\text{kJ/mol}, the relation between them:

Options
  1. a

    x=yx=y

  2. b

    does not exist

  3. c

    x>yx>y

    ✓
  4. d

    x<yx<y

Correct Answerc

x>yx>y

Detailed Solution

🧠 Atomization from liquid adds vaporization on top of bond dissociation Bond enthalpy is defined for gas-phase molecules. Atomization of \ceBr2(l)\ce{Br2(l)} requires first vaporizing the liquid, then breaking the bond — two steps, both endothermic.

x=ΔHvap+yx = \Delta H_{\text{vap}} + y

Since ΔHvap>0\Delta H_{\text{vap}} > 0, it follows that x>yx > y.

Answer: (c) x>y\boxed{\text{Answer: (c) } x > y}

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Thermodynamics) inside The Crucible, our adaptive practice platform.

Practice in The Crucible →Browse Thermodynamics chapter →

More JEE Main Thermodynamics PYQs

2025hard

Total enthalpy change for freezing of 1 mol of water at 10°C to ice at -10°C is _____. Given: fusH = x\ kJ/mol Cp[H2O(l)] = y\ J mol-1K-1 Cp[H2O(s)] = z\ J mol-1K-1

2025easy

One mole of an ideal gas expands isothermally and reversibly from 10 dm3 to 20 dm3 at 300 K. U, q and work done in the process respectively are: Given: R = 8.3 JK-1 and mol-1 In 10 = 2.3, 2 = 0.30, 3…

2024medium

Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Enthalpy of neutralisation of strong monobasic acid with strong monoacidic…

2023medium

Given: (A) 2CO(g) + O2(g) 2CO2(g), H1 = -x\,kJ mol-1 (B) C(graphite) + O2(g) CO2(g), H2 = -y\,kJ mol-1 The H for the reaction C(graphite) + 12O2(g) CO(g) is:

2023medium

The enthalpy change for the adsorption process and micelle formation respectively are:

View all 58 Thermodynamics PYQs →
If enthalpy of atomization for Br2(l) is x\,kJ/mol and bond enthalpy for Br2 is y\,kJ/mol, the… (JEE Main 2020) | Canvas Classes