PYQSide ExamsMy practice

Thermodynamics · Question 54

AIPMT 2006MCQEasy📈 Topic in 38% papers+4−1
1

Assume each reaction is carried out in an open container. For which reaction will H = E?

  1. 2CO(g) + O2(g) 2CO2(g)
  2. H2(g) + Br2(g) 2HBr(g)
  3. C(s) + 2H2O(g) 2H2(g) + CO2(g)
  4. PCl5(g) PCl3(g) + Cl2(g)

Answer

(2) H2(g) + Br2(g) 2HBr(g)

Solution

H = E + ng RT

∴ H = E only when ng = 0 (moles of gaseous products − moles of gaseous reactants).

(1) ng = 2 - 3 = -1

(2) ng = 2 - 2 = 0

(3) ng = 3 - 2 = +1 (solid C is not counted)

(4) ng = 2 - 1 = +1

Answer: (2)

AIPMT 2006

Keep practising — Thermodynamics

2

The enthalpy and entropy change for the reaction: Br2(l) + Cl2(g) 2BrCl(g) are 30 kJ mol-1 and 105 J K-1 mol-1 respectively. The temperature at which the reaction will be in equilibrium is

  1. 300 K
  2. 285.7 K
  3. 273 K
  4. 450 K
AIPMT 2006
3

The enthalpy of hydrogenation of cyclohexene is -119.5 kJ mol-1. If resonance energy of benzene is -150.4 kJ mol-1, its enthalpy of hydrogenation would be

  1. -358.5 kJ mol-1
  2. -508.9 kJ mol-1
  3. -208.1 kJ mol-1
  4. -269.9 kJ mol-1
AIPMT 2006
4

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction ?

  1. Exothermic and increasing disorder
  2. Exothermic and decreasing disorder
  3. Endothermic and increasing disorder
  4. Endothermic and decreasing disorder
AIPMT 2005
5

A reaction occurs spontaneously if

  1. T S < H and both H and S are +ve
  2. T S > H and H is +ve and S is −ve
  3. T S > H and both H and S are +ve
  4. T S = H and both H and S are +ve
AIPMT 2005
6

The absolute enthalpy of neutralisation of the reaction : MgO(s) + 2HCl(aq) MgCl2(aq) + H2O(l) will be

  1. -57.33 kJ mol-1
  2. greater than -57.33 kJ mol-1
  3. less than -57.33 kJ mol-1
  4. 57.33 kJ mol-1
AIPMT 2005
7

If the bond energies of H-H, Br-Br, and H-Br are 433, 192 and 364 kJ mol-1 respectively, the H for the reaction H2(g) + Br2(g) 2HBr(g) is

  1. -261 kJ
  2. +103 kJ
  3. +261 kJ
  4. -103 kJ
AIPMT 2004
8

Standard enthalpy and standard entropy changes for the oxidation of ammonia at 298 K are -382.64 kJ mol-1 and -145.6 J K-1 mol-1, respectively. Standard Gibbs energy change for the same reaction at 298 K is

  1. -221.1 kJ mol-1
  2. -339.3 kJ mol-1
  3. -439.3 kJ mol-1
  4. -523.2 kJ mol-1
AIPMT 2004
9

Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is

  1. Ssystem + Ssurroundings > 0
  2. Ssystem - Ssurroundings > 0
  3. Ssystem > 0 only
  4. Ssurroundings > 0 only
AIPMT 2004
10

The work done during the expansion of a gas from a volume of 4 dm3 to 6 dm3 against a constant external pressure of 3 atm is (1 L atm = 101.32 J)

  1. -6 J
  2. -608 J
  3. +304 J
  4. -304 J
AIPMT 2004
11

For the reaction, C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) at constant temperature, H - E is

  1. +RT
  2. -3RT
  3. +3RT
  4. -RT
AIPMT 2003

All Thermodynamics PYQs →

PDFDownload Thermodynamics PYQs as PDF Free, with answer key and a QR code to every solution — print it or study offline⬇
All NEET Chemistry chapters
Physical ChemistrySome Basic Concepts of ChemistryStructure of AtomStates of MatterThermodynamicsEquilibriumRedox ReactionsSolid StateSolutionsElectrochemistryChemical KineticsSurface Chemistry
Inorganic ChemistryClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular StructureHydrogens-Block Elementsp-Block Elements (Group 13 & 14)Environmental ChemistryGeneral Principles of Isolation of Elementsp-Block Elements (Group 15–18)d- and f-Block ElementsCoordination Compounds
Organic ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismHydrocarbonsHaloalkanes and HaloarenesAlcohols, Phenols and EthersAldehydes, Ketones and Carboxylic AcidsAminesBiomoleculesPolymersChemistry in Everyday LifePrinciples Related to Practical Chemistry