The heats of neutralisation of four acids A, B, C and D are -13.7, -9.4, -11.2 and -12.4 kcal respectively when they are neutralised by a common base. The acidic character obeys the order :

1. A>B>C>D

2. A>D>C>B

3. D>C>B>A

4. D>B>C>A

Subtopic:  Hess's Law |
 92%
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If a process is both endothermic and spontaneous, then :

1. S>0

2. S<0

3. H<0

4. G>0

Subtopic:  Gibbs Energy Change |
 79%
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The bond energies of C=C and C-C at 298 K are 590 and 331 kJ mol-1 respectively. The enthalpy of polymerization per mole of ethylene is

1. -70 kJ

2. -72 kJ

3. 72 kJ

4. -68 kJ

Subtopic:  Thermochemistry |
 72%
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The gas absorbs 100 J heat and is simultaneously compressed by a constant external pressure of 1.50 atm from 8 lit. to 2 lit. in volume. Hence E will be-

1. -812 J

2. 812 J

3. 1011 J

4. 911 J

Subtopic:  Enthalpy & Internal energy |
 55%
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The standard heat of combustion of Al is -837.8 kJ mol-1 at 25C which of the following releases 250 kcal of heat ?

1. The reaction of 0.624 mol of Al

2. The formation of 0.624 mol of Al2O3

3. The reaction of 0.312 mol of Al

4. The formation of 0.150 mol of Al2O3

Subtopic:  Thermochemistry |
 65%
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Following reaction occurs at 25C :

2NOg, 1×10-5 atm+Cl2g, 1×10-2 atm2NOClg, 1×10-2 atmG is :

1. -45.65 kJ

2. -28.53 kJ

3. -22.82 kJ

4. -57.06 kJ

Subtopic:  Gibbs Energy Change |
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The bond energies ofCC, C-H, H-H and C=C are 198, 98, 103 and145 kcal respectively. The enthalpy change of the reaction HCCH+H2C2H4 is:

1. 48 kcal

2. 96 kcal

3. -40 kcal

4. -152 kcal

Subtopic:  Enthalpy & Internal energy |
 76%
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The enthalpies of formation of CO2(g) and CO(g) at 298 K are in the ratio 2.56 : 1. For the reaction,

CO2(g)+C(s)2CO(g), H=177.5kJ,
Hf of CO(g)  is-

1. -150.6 kJ mol-1

2. -113.78 kJ mol-1

3. -130.2 kJ mol-1

4. -141.8 kJ mol-1

Subtopic:  Enthalpy & Internal energy |
 61%
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The enthalpies of the following reactions are shown alongwith.

12H2g+12O2gOHg ; H=42.09 kJ mol-1
H2g2Hg;                      H=435.89 kJ mol-1
O2g2Og;                      H=495.05 kJ mol-1

Calculate the O-H bond energies for the hydroxyl radical.

1. 223.18 kJ mol-1

2. 423.38 kJ mol-1

3. 513.28 kJ mol-1

4. 113.38 kJ mol-1

Subtopic:  Thermochemistry |
 76%
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4.8 g of C(diamond) on complete combustion evolves 1584 kJ of heat. The standard heat of formation gaseous carbon is 725 kJ/mol. The energy required for the process

(i) C(graphite)C(gas)

(ii) C(diamond)C(gas)are

1. 725, 727

2. 727, 725

3. 725, 723

4. None of these

Subtopic:  Hess's Law |
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