Which one of the following sets of units represents the smallest and the largest amount of energy respectively ?
eV and lit atm
erg and cal
cal and eV
lit atm and J
A gas expands from a volume of 1 m3 to a volume of 2 m3 against an external pressure of 105 N m-2. The work done by the gas will be
105kJ
102kJ
102J
103J
Calculate the work done (in joules) when 0.2 mole of an ideal gas at 300 K expands isothermally and reversibly from initial volume of 2.5 litres to the final volume of 25 litres
996
1148
11.48
114.8
Calculate the work done when 1 mole of an ideal gas is compressed reversibly from 1.0 bar to 4.00 bar at constant temperature of 300 K
3.458 kJ
- 8.20 kJ
18-02 kJ
- 14-01 kJ
If w is the amount of work done by the system and q is the amount of heat supplied to the system, identify the type of the system
isolated system
closed system
open system
system with thermally conducting walls
Changes in a system from an initial state to the final state were made by a different manner that ∆H remains same but a changes because
∆H is a path function but q is a state function
∆H is a state function and q is a path function
Both ∆H and g are state function
Both ∆H and q are path function
A piston filled with 0.04 mol of an ideal gas expands reversibly from 50.0 mL to 375 mL at a constant temperature of 37.0°C.As it does so, it absorbs 208 J of heat. The values of q and w for the process will be: (R = 8.314 J/mol K, In 7.5 = 2:01)
q = + 208 J, W = + 208 J
q = + 208 J, W = - 208 J
open system
system with thermally conducting walls
Which of the following is correct option for free expansion of an ideal gas under adiabatic condition?
q = 0, ∆T < 0, w ≠ 0
q = 0, ∆T ≠ 0 w=0
q ≠ 0, ∆T = 0, w = 0
q = 0, ∆T = 0, w=0
When 1 mol of a gas is heated at constant volume, temperature is raised from 298 to 308 K. Heat supplied to the gas is 500 J. Then which statement is correct?
q = W = 500 J, ∆U = 0
q = ∆U = 500 J, W = 0
q = W = 500 J, ∆U = W = 0
∆U = 0, q = W = - 500 J
Which one of the following equations does not correctly represent the first law of thermodynamics for the given process?
Isothermal process: q =- w
Cyclic process: q =- w
Isochoric process: ∆E = q
Adiabatic process: ∆E =- W
∆E is always positive when
System absorbs heat and work is done on it
System emits heat and work is done on it
System emits heat and no work is done on it
System absorbs heat and work is done by it
Based on first law of thermodynamics, which one of the following is correct?
For an isochoric process, ∆ U = -q
For an adiabatic process, ∆ U =-w
For an isothermal process, q = + W
For a cyclic process, q = -w
Standard enthalpy of vaporisation ∆vapH° for water at 100°C is 40.66kJmol-1.The internal energy change of vaporisation of water at 100°C (in kJ mol-1) is :
+ 37.56
– 43.76
+ 43.76
+ 40.66
The value of enthalpy change (∆H) for the reaction C2H5OH (l) + 3 O22 (g) → 2 CO2 (g) + 3 H2O (l) at 27°C is – 1366.5 kJ mol-1. The value of internal energy change for the above reaction at this temperature will be
- 1371.5 kJ
- 1369.0 kJ
- 1364.0 kJ
- 1361.5 kJ
One mol of a non-ideal gas undergoes a change of state (2.0 atm, 3.0 L, 95 K) – (4.0 atm, 5.0 L, 245 K) with a change in internal energy, ∆U = 30.0L atm. The change in enthalpy (∆H) of the process in L atm is
40.0
42.3
44.0
Not defined, because process is not constant
In a constant volume process, internal energy change is equal to
heat transferred
work done
zero
none of these
Change in enthalpy of a system is due to heat supplied at
constant volume
constant pressure
both at constant volume and pressure
none of these
The enthalpy and internal energy are the function of temperature for
all gases
steam
water
ideal gas
Any series of operations so carried out that at the end, the system is back to its initial state is called
Boyle's cycle
Reversible process
Adiabatic process
Cyclic process
One calorie is equal to [CPMT 1988]
0.4184 Joule
4.184 Joule
41.84 Joule
418.4 Joule
The total internal energy change for a reversible isothermal cycles is
Always 100 calories per degree
Always negative
0
Always positive
Identify the intensive quantity from the following [IIT JEE 1993]
Enthalpy and temperature
Volume and temperature
Enthalpy and volume
Temperature and refractive index
The relation between ΔE and ΔH is [MP PET 1992; MP PMT 1996; MP PET/PMT 1998]
ΔH=ΔE−PΔV
ΔH=ΔE+PΔV
ΔE=ΔV+ΔH
ΔE=ΔH+PΔV
The law of Lavoisier and Laplace illustrates [KCET 1989]
The principle of conservation of energy
Equivalence of mechanical and thermal energy
The principle of conservation of matter
Equivalence of mechanical and chemical energy
For the reaction N2+3H2⇌2NH3; ΔH= [Roorkee 2000; CBSE PMT 1991, 2002]
ΔE−RT
ΔE−2RT
ΔE+RT
ΔE+2RT
Hess's law of constant heat summation in based on [MP PET 2001]
E=mc2
Conservation of mass
First law of thermodynamics
None of these
Hess law is applicable for the determination of heat of [AIIMS 1998; Pb. PET/PMT 1999]
Reaction
Formation
Transition
All of these
Hess law of heat summation includes [AFMC 1992]
Initial reactants only
Initial reactants and final products
Final products only
Intermediates only
The work done during the expansion of a gas from a volume of 4dm3 to 6dm3 against a constant external pressure of 3atm is (1Latm=101.32J) [CBSE PMT 2004]
+ 304 J
-304 J
- 6 J
-608 J
The work done in ergs for the reversible expansion of one mole of an ideal gas from a volume of 10 litres to 20 litres at 25°C is [CMC Vellore 1991]
2.303×298×0.082 log2
298×107×8.31×2.303 log2
2.303×298×0.082 log0.5
8.31×107×298−2.303 log0.5
For a reversible spontaneous change ΔS is
ΔE/T
(P ΔV)/T
q/T
RT× log K
When disorder of a system increases, the change is said to be
Exothermic
Non-spontaneous
Endothermic
Spontaneous
The spontaneous flow of heat is always
From low to high pressure
From high to high pressure
Unidirectional from lower temperature to higher temperature
Unidirectional from the higher to lower temperature
Mixing of non-reacting gases is generally accompanied by
Decrease in entropy
Increase in entropy
Change in enthalpy
Change in free energy
The entropy values (in JK-1 mol-1) of H2(g) = 130.6, Cl2(g) = 223.0 and HCl(g) = 186.7 at 298 K and 1 atm pressure. Then entropy change for the reaction H2 (g) +Cl2 (g) →2HCl (g) is [BHU 2005]
+ 540.3
+ 727.3
- 166.9
+ 19.8
Which of the following is the least random state of water
Ice
Liquid water
Steam
All present same random state
Which of the following is zero during adiabatic expansion of the gas
∆T
ΔS
ΔE
None of these
The entropy of crystalline substances at absolute zero going by the third law of thermodynamics should be taken as [J & K 2005]
100
50
Zero
Different for different substances
In which state, the matter have highest entropy
Solid
Liquid
Gas
Equal in all
The ΔS for the vaporisation of 1 mol of water is 88.3 J/mole K. The value of ΔS for the condensation of 1 mol of vapour will be
88.3 J/mol K
(88.3)2 J/mol K
- 88.3 J/mol K
188.3 J/mol K
For which reaction from the following, ΔS will be maximum [AlIMS 1982, 83, 94; AMU 2000]
Ca(s)+12O2(g)→CaO(s)
CaCO3(s)→CaO(s)+CO2(g)
C(s)+O2(g)→CO2(g)
N2(g)+O2(g)→2NO(g)
If the enthalpy of vaporization for water is 186.5 kJ mol-1, the entropy of its vaporization will be [CPMT 1988; DCE 2000]
0.5JK-1mol-1
1.0JK-1mol-1
1.5JK-1mol-1
2.0JK-1mol-1
For chemical reactions, the calculation of change in entropy is normally done
At constant pressure
At constant temperature
At constant temperature and pressure both
At constant volume
When the value of entropy is greater, then the ability of work
Is maximum
Is minimum
Is medium
None of these
When a solid is converted into liquid, entropy [MP PET 1993, 95; MP PMT 1996]
Becomes zero
Remains the same
Decreases
Increases
In a spontaneous process, the entropy of the system and its surroundings [MP PET 1996; NCERT 1975]
Equals zero
Decreases
Increases
remains constant
The positive value of ΔS indicates that [MP PMT 1997]
The system becomes less disordered
The system becomes more disordered
The system is in equilibrium position
The system tends to reach at equilibrium position
The enthalpy of water is 386kJ. What is entropy of water [BHU 1997]
0.5 kJ
1.30 kJ
1.5 kJ
22.05 kJ
One mole of an ideal gas at 300K is expanded isothermally from an initial volume of 1 litre to 10 litres. The change in energy for this process is (R=2calmol-1K-1) [CBSE PMT 1998]
163.7 cal
850.2 cal
1381.1 cal
Zero
A container has hydrogen and oxygen mixture in ratio of 4: 1 by weight, then [BHU 1998]
Internal energy of the mixture decreases
Internal energy of the mixture increases
Entropy of the mixture increases
Entropy of the mixture decreases
In which of the following conditions a chemical reaction can not occur [AMU 1999]
ΔH and ΔS increase and TΔS>ΔH
ΔH and ΔS decrease and ΔH>TΔS
ΔH increases and ΔS decreases
ΔH decreases and ΔS increases
An engine operating between 150°C and 25°C takes 500 J heat from a higher temperature reservoir if there are no frictional losses, then work done by engine is [MH CET 1999]
147.7 J
157.75 J
165.85 J
169.95 J
The entropy of a perfectly crystalline solid at absolute zero is [AMU 2000]
Positive
Negative
Zero
Not definite
The volume of a gas decreases from 500cc to 300cc when a sample of gas is compressed by an average pressure of 0.6 atm. During this process 10 J of heat is liberated. The change in internal energy is [Pb. PMT 2000]
- 2.16 J
12.156 J
2.16 J
101.3 J
Which of the following endothermic processes is/are spontaneous [CBSE PMT 2001]
Melting of ice
Evaporation of water
Heat of combustion
Melting of ice and Evaporation of water
If C+O2→CO2 + 94.2kcal H2+12O2→H2O + 68.3kcal CH4+2O2→CO2+2H2O + 210.8kcal then the possible heat of methane will be [MP PET 1990]
47.3 kcal
20.0 kcal
45.9 kcal
-47.3 kcal
The enthalpy of fusion of ice per mole
18 kJ
8 kJ
80 kJ
6 kJ
In which of the following neutralisation reactions, the heat of neutralisation will be highest [MP PMT 1989, 91; AIIMS 1999]
NH4OH and CH3COOH
NH4OH and HCl
NaOH and CH3COOH
NaOH and HCl
From Kirchhoff's equation which factor affects the heat of reaction [MP PMT 1990]
Pressure
Temperature
Volume
Molecularity
The molar neutralization heat for KOH and HNO3 as compared to molar neutralization heat of NaOH and HCl [MP PMT 1989]
Less
More
Equal
Depends on pressure
An exothermic reaction is one in which the reacting substances [CPMT 1974, 79; Bihar MEE 1982; KCET 1992; JIPMER 2001]
Have more energy than the products
Have less energy than the products
Are at a higher temperature than the product
None of these
Which of the following statement is correct [NCERT 1978]
ΔH is positive for exothermic reaction
ΔH is negative for endothermic reaction
The heat of neutralization of strong acid and strong base is always the same
The enthalpy of fusion is negative
If the enthalpy of B is greater than of A, the reaction A→B is [MP PMT 1997]
Endothermic
Exothermic
Instantaneous
Spontaneous
Enthalpy change for reaction, 1/2H2+1/2Cl2→HCl, is called
Enthalpy of combination
Enthalpy of reaction
Enthalpy of formation
Enthalpy of fusion
The enthalpy of neutralization is about 57.3 kJ for the pair
HCl and NH4OH
NH4OH and HNO3
HCl and NaOH
CH3COOH and NaOH
The heat of reaction does not depend upon
Temperature of the reaction
Physical state of reactants and products
Whether the reaction is carried out at constant pressure or at constant volume
The method by which the final products are obtained from the reactants
Heat of neutralisation of a strong acid by a strong base is a constant value because [KCET 1984]
Salt formed does not hydrolyse
Only H+ and OH- ions react in every case
The strong base and strong acid react completely
The strong base and strong acid react in aqueous solution
Heat of neutralisation of an acid by a base is highest when [KCET 1985]
Both the acid and base are weak
Both the acid and base are strong
The acid is strong and the base is weak
The acid is weak and the base is strong
Heat of combustion of a substance [CPMT 1987, 96; AFMC 1992]
Is always positive
Is always negative
Is equal to heat of formation
Nothing can be said without reaction
The heats of combustion of rhombic and monoclinic sulphur are respectively 70960 and 71030 calories. What will be the heat of conversion of rhombic sulphur to monoclinic [MP PMT/PET 1988]
70960 calories
71030 calories
- 70 calories
+ 70 calories
Which of the following fuels will have the highest calorific value (kJ/kg) [MP PMT 1990]
Charcoal
Kerosene
Wood
Dung
The free energy change for a reversible reaction at equilibrium is [NCERT 1984; Kurukshetra CEE 1998; AMU 1999]
Large positive
Small negative
Small positive
0
For a spontaneous change, free energy change ΔG is [MNR 1983; BHU 1981, 95; AMU 1999; DCE 2000, 01; BHU 2000; MP PMT 2003]
Positive
Negative
Zero
Can be positive or negative
A minus sign of the free energy change denotes that
The reaction tends to proceed spontaneously
The reaction is non-spontaneous
The system is in equilibrium
The reaction is very much unlikely
The relation between ΔG and ΔH is [MP PMT 1994, 95, 97; AFMC 1997; Kurukshetra CEE 1998]
ΔH=ΔG−TΔS
ΔG=ΔH−TΔS
TΔS−ΔG=ΔH
ΔH=TΔG+ΔS
The relation ΔG=ΔH−TΔS was given by [MP PMT 2000; KCET 2002]
Boltzmann
Faraday
Gibbs’Helmholtz
Thomson
For precipitation reaction of Ag+ ions with NaCl, which of the following statements is correct [CPMT 1988]
ΔH for the reaction is zero
ΔG for the reaction is zero
ΔG for the reaction is negative
[ΔG]=[ΔH]
At constant pressure and temperature, the direction to the result of any chemical reaction is where, there is less amount of
Entropy
Enthalpy
Gibb's free energy
None of these
What is the free energy change ΔG when 1.0mole of water at 100°C and 1atm pressure is converted into steam t 100°C and 1atm pressure [MP PET/PMT 1998]
540cal
−9800cal
9800cal
0cal
ΔG° for the reaction X+Y⇌ Z is - 4.606 kcal. The value of equilibrium constant of the reaction at 227°C is (R=2.0cal.mol−1K−1) [Roorkee 1999]
100
10
2
0.01
Spontaneity of a chemical reaction is decided by the negative change in [MP PET 2001]
Internal energy
Enthalpy
Entropy
Free energy
Born-Haber cycle is used to determine [UPSEAT 2001]
Crystal energy
Electron affinity
Lattice energy
All of these
The essential condition for the feasibility of a reaction is that [JIPMER 2002]
The reaction should be exothermic
The entropy of products must be larger than that of reactants
The reaction is to be accompanied with free energy decrease
The reaction has to possess high activation energy
The correct relationship between free energy change in a reaction and the corresponding equilibrium constant Kc is [AIEEE 2003]
ΔG=RTlnKc
−ΔG=RTlnKc
ΔG°=RTlnKc
−ΔG°=RTlnKc
Adsorption of gases on solid surface is generally exothermic because [IIT JEE (Screening) 2004]
Enthalpy is positive
Entropy decreases
Entropy increases
Free energy increase
Two mole of an ideal gas is expanded isothermally and reversibly from 1 litre ot 10 litre at 300K. The enthalpy change (in kJ) for the process is [IIT JEE (Screening) 2004]
11.4 kJ
-11.4 kJ
0 kJ
4.8 kJ
Heat of neutralization of strong acid against strong base is constant and is equal to [EAMCET 1980; AFMC 1989; DPMT 1991; MP PET 1999; BHU 1999; MP PMT 1995]
13.7 kcal
57 kJ
5.7×104 J
All of these
When a gas undergoes adiabatic expansion, it gets cooled due to [DCE 2002]
Loss of kinetic energy
Fall in temperature
Decrease in velocity
Energy used in doing work
The heat content of a system is called
Internal energy
Entropy
Free energy
Enthalpy
The enthalpy change for the reaction of 50.00 ml of ethylene with 50.00 ml of H2 at 1.5 atm pressure is ΔH=−0.31kJ. The value of ΔE will be [DPMT 2004]
-0.3024 kJ
0.3024 kJ
2.567 kJ
-0.0076 kJ
The total amount of energy in the universe is fixed, but [AMU (Engg.) 1999]
Disorder is increasing
Lightning is increasing
Matter is increasing
Gravitation is decreasing
The enthalpies of formation of Al2O2 and Cr2O2 are −1596kJ and −1134kJ respectively. ΔH for the reaction 2Al+Cr2O2→2Cr+Al2O2 is [KCET 2003]
−2730kJ
−462kJ
−1365kJ
+2730kJ
Heat of reaction at constant volume is measured in the apparatus
Bomb calorimeter
Calorimeter
Pyknometer
Pyrometer
A Beckmann thermometer is used to measure [Kurukshetra CEE 2002]
High temperature
Low temperature
Normal temperature
All temperature
The heat required to raise the temperature of a body by 1 K is called [AIEEE 2002]
Specific heat
Thermal capacity
Water equivalent
None of these
The quantity of heat which must be supplied to decompose a compound into its element is equal to the heat evolved during the formation of that compound from the elements. This statement is known as
Hess's law
Joule's law
Le chatelier's principle
Lavoiser and Laplace law
The enthalpy of neutralization of HCN by NaOH is −12.13kJmol−1. The enthalpy of ionisation of HCN will be [BHU 1997]
4.519 kJ
45.10 kJ
451.9 kJ
45.19 kJ
Energy required to dissociate 4 gm of gaseous hydrogen into free gaseous atoms is 208 kcal at 25°C. The bond energy of H−H bond will be [CPMT 1989; MP PET 2000; J & K 2005]
104 kcal
10.4 kcal
1040 kcal
104 cal
The first ionization energy for Li is 5.4 eV and electron affinity of Cl is 3.61eV. The ΔH (in kJ/mol) for the reaction Li(g)+Cl(g)→Li++Cl− is (if resulting ions do not combine with each other) (1eV=1.6×10−19J) [MP PMT 2000, 03]
70
100
170
270
The H−H bond energy is 430 kJ mol and Cl−Cl bond energy is 240kJmol−1 ΔH for HCl is −90kJ. The H−Cl bond energy is about [BVP 2003]
180kJmol−1
360kJmol−1
213kJmol−1
425kJmol−1
The work done during the expansion of a gas from a volume of against a constant external pressure of 3 atm is (1 atm-L=101.32 J)
-6 J
-608 J
304 J
-304 J
The bond energies of are 433,192 and 364 kJ/mol respectively. The for the reaction is
- 261 kJ
103 kJ
261 kJ
- 103 kJ
The absolute enthalpy of neutralization of the reaction, will be
Greater than - 57.33 kJ/mol
Less than - 57.33 kJ/mol
- 57.33 kJ/mol
- 157.33 kJ/mol
A reaction occurs spontaneously if :
and both are positive
and both are positive
and both are positive
and is positive and is negative
Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?
Exothermic and decreasing disorder
Endothermic and increasing disorder
Exothermic and increasing disorder
Endothermic and decreasing disorder
Identify the correct statement for change of Gibbs energy for a system at constant temperature and pressure:
If , the system is still moving in a particular direction
If , the process is not spontaneous
If , the process is spontaneous
If , the system has attained equilibrium
The enthalpy and entropy change for the reaction,
are 30 kJ/mol and 105 respectively. The temperature at which the reaction will be in equilibrium is :
450 K
300 K
285.7 K
273 K
Assume each reaction is carried out in an open container. For which reaction will ?
The enthalpy of combustion of , cyclohexene and cyclohexane are 241, 3800 and 3920 kJ per mol respectively. Heat of hydrogenation of cyclohexene is
- 121 kJ per mol
+ 121 kJ per mol
+ 242 kJ per mol
+ 242 kJ per mol
The enthalpy of hydrogenation is - 119.5 kJ per mol. If the resonance energy of benzene is - 150.4 kJ per mol, its enthalpy of hydrogenation would be
- 269.9 kJ per mol
- 358.5 kJ per mol
- 508.9 kJ per mol
- 208.1 kJ per mol
Identify the correct statement regarding a spontaneous process
Lowereing of energy is the only criterion for spontaneity
For a spontaneous process in an isolated system, the change in entropy is positive
- 508.9 kJ per mol
- 208.1 kJ per mol
The bond energy is 430kJ per mol and bond energy is 240 kJ per mol. for is -90 kJ. The bond energy is about
425 kJ per mol
213 kJ per mol
306 kJ per mol
180 kJ per mol
When 1 mole of gas is heated at constant volume.Temperature is raised from 298 to 308K.Heat supplied to the gas is 500J.Then which statement is correct? (AIPMT/NEET 2001)
Most probable oxidation states of Pb and Sn will be (AIPMT/NEET 2001)
Change in enthalpy for reaction
if heat of formation of and are -188 and -286 kJ/mol respectively is (AIPMT/NEET 2001)
-196 kJ/mol
+196 kJ/mol
+948 kJ/mol
-948 kJ/mol
Enthalpy of is respectively negative.If enthalphy of combustion of are x and y respectively, then which relation is correct? (AIPMT/NEET 2001)
x>y
x<y
x=y
The unit of entropy is (AIPMT/NEET 2002)
Calculate the maximum efficiency of an engine operating between 110°C and 25°C.
11.1%
22.2%
33.3%
44.4%
Two moles of ideal gas at temperature is expanded reversibly from 2 litres to 20 litre.Find entrophy change (R=2cal/molK). (AIPMT/NEET 2002)
92.1
0
4
9.2
Heat of combustion for C(s), and are -94,-68 and -213 kcal/mol.Then for is (AIPMT/NEET 2002)
-17kcal
-111kcal
-170kcal
-85kcal
The molar heat capacity of water at constant pressure P,is .When 1.0KJ of heat is supplied to 100g of water which is free to expand,the increase in temperature of water is (AIPMT/NEET 2003)
1.2K
2.4K
4.8K
6.6K
What is the entrophy change when one mole of ice is converted into water at ? (The enthalphy change for the conversion of ice to liquid water is at ) (AIPMT/NEET 2003)
20.13
2.013
2.198
21.98
Identify the correct statement for change of gibbs energy for a system at constant temeperature and pressure. (AIPMT/NEET 2006)
if the system is still moving in a particular direction.
if the process is not spontaneous
if the system is spontaneous.
if , the system has atttained equlibrium.
The enthalphy and entrophy change for the reaction,
are 30KJ and 105 J respectively.The temperature at which the reaction will be in equilibrium (AIPMT/NEET 2006)
450K
300K
285.7K
273K
Assume each reaction is carried out in an open container.For which reaction will (AIPMT/NEET 2006)
The enthalphy of combustion of ,Cyclohexene and cyclohexene are 241`, 3800 and 3920KJ per mol respectively heat of hydrogenation of cyclohexne is (AIPMT/NEET 2006)
-121 KJ per mol
+121 KJ per mol
+242 KJ per mol
-242KJ per mol
The enthalphy of hydrogenation of cyclohexene is -119.5KJ/mol.If resonance energy of benzene is -150.4KJ/mol its enthalphy of hydrogenation would be (AIPMT/NEET 2006)
-269.9KJ/mol
-358.5KJ/mol
-508.9KJ/mol
-208.1KJ/mol
Identify the correct statement regarding a spontaneous process (AIPMT/NEET 2007)
Loweering of energy is the only criterion for spontaneity.
For a spontaneous process in an isolated system,the change in entrophy is positive.
Endothermic processes are never spontaneous
Exothermic process are always spontaneous
The H-H bond energy is 430KJ/mol and Cl-Cl bond energy is 240KJ/mol. For HCl is -90 KJ.The H-Cl bond energy is about (AIPMT/NEET 2007)
425KJ/mol
213KJ/mol
306KJ/mol
180KJ/mol
Which of the following are not state functions? 1) q + w 2)q 3) w 4) H-TS (AIPMT/NEET 2008)
(2) ,(3) and (4)
(1) ,(2) and (3)
(2) and (3)
(1) and (4)
For the gas phase reaction
which of the following conditions are correct? (AIPMT/NEET 2008)
Bond dissociation enthalphy of are 4434,242 and 431KJ/mol respectively.Enthalphy of formation of HCl is (AIPMT/NEET 2008)
-245KJ/mol
-63KJ/mol
245KJ/mol
-93KJ/mol
Calculate the maximum efficiency of an engine operating between
11.1%
22.2%
33.3%
44.4%
Five moles of an ideal gas expands reversibly from a volume of at a temperature of .Claculate the change in entrophy
70.26J/K
82.55J/K
95.73K/J
107.11J/K
Entrophy change involved in conversion of 1 mole of liquid water at 373K to vapour at the same temperature(latent heat of vaporization of water = 2.257KJ/g)
30.7
60.3
90.8
108.9.
What is the value of (heat change at constant volume) for reversible isothermal evaporation of 90g water at .Assuming water vapour behaves as an ideal gas and .
4.49cal
none of these
Which of the statement is correct?
slope of adiabatic P-V curve will be the same as that of isothermal one.
slope of adiabatic P-V curve is smaller than that in isothermal one.
slope of adiabatic P-V curve is larger than that in isothermal one.
slope of adiabatic P-V curve may be smaller or larger depending on the value V.
The specific heats of iodine vapour and solid are 0.031 and 0.055cal/g respectively.If specific heat of iodine is 24cal/g at . Calculate its value at
5.7cal/g
11.4cal/g
22.8cal/g
45.6cal/g
Bond dissociation energy of bond is 103kcal/mol and heat of formation of is -17.88kcal/mol.The heat of formation of methyl radical is
3.61kcal/mol
-3.61kcal/mol
33.61kcal/mol
-33.61kcal/mol
For the combustion of n-octane (Ignoring resonance in )
The work done in ergs for the reversible expansion of 1mole of an ideal gas from a volume of 10litres to 20 litres at 25 deg celsius is
If 900J/g of heat is exchanged at boiling point of water then what is the increase in entrophy
43.4J/mol
87.2J/mol
900J/mol
Zero
The enthalphy of formation of is -285.77KJ//mol and enthalphy of neutralization of strong acid and strong base is -56.07KJ/mol,what is the enthalphy of formation of ion
+229.70KJ
-229.70KJ
+226.70KJ
-22.670KJ
One gram sample of is decomposed in a bomb calorimeter.The temperature of the calorimeter increases by 6.12K.The heat capcity of the system is 1.23KJ/g deg.What is the molar heat of decomposition for ? (AIIIMS 2013)
-7.53kJ/mol
-398kJ/mol
-16.1kJ/mol
-602kJ/mol
The quantity of heat which must be supplied to decompose a compound into its element is equal to the heat evolved during the formation of that compound from the elements"This statement is known as
Hess s law
Joules law
Le-chateliers principle
Lavoisier and Laplace law.
Which of the following has lowest fusion temperature?
Naphthalene
Diamond
NaCl
Mn
For conversion C(graphite) C(diamond) the is
Zero
positive
negative
unknown
Assertion: Absolute values of internal energy of substance cannot be determined. Reason: It is impossible to determine exact values of constituent energies of the substances.
both the assertion and reason are true and reason is the true explanation of the assertion.
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true.
Assertion:The increase in internal energy for the vaporization of one mole of water at 1atm and 373K is zero. Reason: For all isothermal processes .
both the assertion and reason are true and reason is the true explanation of the assertion.
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true.
Assertion: The enthalphies of neutralization of strong acids and strong bases are always same. Reason: Neutralisation is heat of formation of water
both the assertion and reason are true and reason is the true explanation of the assertion.
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true.
Assertion: Phase transition involves change in internal energy only. Reason: Phase transition occurs at constant pressure.
both the assertion and reason are true and reason is the true explanation of the assertion.
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true
Assertion: The SI unit of entrophy is . Reason: .
both the assertion and reason are true and reason is the true explanation of the assertion.
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true.
Assertion: The change in entrophy during melting of ice is negligible in comparison to change in entrophy during vaporisation. Reason: The volume occupied by solid and liquid is too less in comparison to volume occupied by gas.
both the assertion and reason are true and reason is the true explanation of the assertion.
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true.
Assertion: Molar entrophy of vaporization of water is different from ethanol. Reason: Water is more polar than ethanol.
both the assertion and reason are true and reason is the true explanation of the assertion
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true.
Assertion: The increase in internal energy for the vaporisation of 1 mole of water at 1 atm and 373K is zero. Reason: For all isothermal processes
both the assertion and reason are true and reason is the true explanation of the assertion
both the assertion and reason are true but the reason is not the correct explanation of assertion.
the assertion is true but reason is false
assertion is false but reason is true.
Calculate the reasonance energy of from the following data observed B.E of N =N 946kJ/mol; B.E of N =N 418kJ/mol B.E of O=O 498kJ/mol ; B.E N =O 607kJ/mol
-88kJ/mol
-44kJ/mol
-22kJ/mol
None of these
If at 298K the bond energies of C-H,C-C,C=C and H-H bonds are respectively 414,347,615 and 435kJ/mol the value of enthalphy change for the reaction at 298K will be
+250kJ
-250kJ
+125kJ
-125kJ
The enthalpies of formation of and are -1596kJ and -1134kJ respectively. for the reaction is
-2730kJ
-462kJ
-1365kJ
+2730kJ
At ice and water are in equilibrium and for the conversion of ice to liquid water is
-ve,zero
zero,zero
Which of the following is not a state function?
Internal energy
Enthalpy
Work
Entropy
Among them intensive property is
mass
volume
surface tension
enthalpy
At constant T and P, which one of the following statements is correct for the reaction.
is independent of the physical state of the reactants of that compound
For the reaction of one mole of zinc dust with one mole of sulphuric acid in a bomb calorimeter, and w corresponds to
Which of the following expressions represents the first law of thermodynamics?
The realtion between change in internal energy, change in enthalpy and work done(W) is represented as
Work done during isothermal expansion of one mole of an ideal gas from 10 atm at 300 K is (Gas constant=2)
938.8 cal
1138.8 cal
1381.8 cal
1581.8 cal
Internal energy is
partly potential and partly kinetic
totally kinetic
totally potential
none of these
For which reaction from the following, will be maximum
The occurance of a reaction is impossible if
Which of the following is true for the reaction and 1 atmosphere
Following data is known about melting of a compound AB. . Its melting point is
736 K
1050 K
1150 K
One mole of an ideal gas is allowed to expand reversibily and adiabatically from a temperature of . If the work done during the process is 3 kJ, the final temperature will be equal to
150 K
100 K
295 K
Equal volumes of monoatomic and diatomic gases of same initial temperature and pressure are mixed. The ratio of specific heats of mixture will be
1
2
1.67
1.5
Which one of the following has greater than zero?
The heat of neutralization of a strong acid and a strong alkali is 57.0 kJ per mol. The heat released when 0.5 mole of solution is mixed with 0.2 mol of KOH is
57.0 kJ
11.4 kJ
28.5 kJ
34.9 kJ
If enthalpies of formation of and 1 am pressure be 52, -394 and -286 kJ per mol respectively, the enthalpy of combustion of will be
+1412 kJ per mol
-1412 kJ per mol
+141.2 kJ per mol
-141.2 kJ per mol
Combustion of glucose takes place according to the question, . How much energy will be required for the production of 1.6 g of glucose? (Molecular mass of glucose = 180 g)
0.064 kcal
0.64 kcal
6.4 kcal
64 kcal
Ozone is prepared by passing silent electric discharge through oxygen. In this reaction
energy is given out
energy is absorbed
oxygen is loaded with energy
oxygen is dissociated into atoms
When a 4g of iron is burnt to ferric oxide at constant pressure, 29.28 kJ of heat is evolved. What is the enthalpy of formation of ferric oxide (At.wt of Fe = 56)
-81.98 kJ
-819.8 kJ
-40.99 kJ
+819.8 kJ
Enthalpy of neutralization of acetic acid by NaOH is -50.6 kJ/mol and the heat of neutralization of a strong acid with a strong base is -55.9 kJ/mol. What is the value of for the ionisation of ?
+5.3 kJ/mol
+6.2 kJ/mol
+8.2 kJ/mol
+9.3 kJ/mol
The enthalpy of combustion of is -3250 kJ. When 0.39 g of benzene is burnt excess of oxygen in an open vessel, the amount of heat evolved is
16.25 J
16.25 kJ
32.5 J
32.5 kJ
One gram sample of is decomposed in a bomb calorimeter. the temperatuire of the calorimeter increases by 6.12 K. The heat capacity of the system is 1.23 kJ/g/deg. What is the molar heat of decomposition for ?
-7.53 kJ/mol
-398.1 kJ/mol
-16.1 kJ/mol
-602 kJ/mol
In which of the following neutralization reactions, the heat of neutralization will be higher?
From the following bond energies H-H bond energy: 431.37kJ/mol C=C bond energy: 606.10kJ/mol C--C bond energy: 336.49kJ/mol C--H bond energy: 410.50kJ/mol Enthalphy for the reaction
553.0kJ/mol
1523.6kJ/mol
-243.6kJ/mol
-120.0kJ/mol
Three moles of an ideal gas expanded spontaneously into vaccum.The work done will be
Infinite
3joules
9joules
Zero
For vaporization of water at 1 atmospheric pressure the values of are 40.63kJ/mol and 108.8J/K/mol respectively.The temperature when gibbs energy change for this transformation will be zero is
273.4K
393.4K
373.4K
293.4K
The following two reactions are known
The value of for the following reaction is
+10.3kJ
-43.3kJ
-10.3kJ
6.2kJ
Which of the following is the correct option for the free expansion of an ideal gas under adiabatic condition?
Enthalphy change for the reaction,
The dissociation energy of H---H bond is
+217.4kJ
-434.8kJ
-869.6kJ
+434.8kJ
Standard enthalphy of vaporisation for water at is 40.66kJ/mol .The internal energy of vaporization of water (inkJ/mol) is
+43.76
+40.66
+37.56
-43.76
The enthalphy of fusion of water is 1.435kcal/mol.The molar entrophy change for the melting of ice at is
5.260 cal/(mol K)
0.526cal/(mol K)
10.52cal/(mol K)
21.04cal/(mol K)
In which of the following reactions,standard reactions entrophy change is positive and standard gibbs energy change decreases sharply with increasing temperature?
Equal volume of two monoatomic gases,A and B at the same temperature and pressure are mixed.The ratio of specific heats of the mixture will be
0.83
1.50
3.3
1.67
A reaction having energies of atom for forward and reverse reaction has
Which of the following statements is correct for the spontaneous adsorption of gas?
is neagtive and therefore, should be highly positive
is negative and therefore , should be highly negative.
is positive and therfore , should be negative
is postive and therefore, should also be highly positive
For the reaction
Hence is
2.7kcal
-2.7kcal
9.3kcal
-9.3kcal
Given
The enthalphy of hydrogenation of these compounds will be in the order is
The heat of combustion of carbon to is -393.5 kJ/mol.The heat released upon the formation of 35.2g of from carbon and oxygen gas is
-630kJ
-3.15kJ
-315kJ
+315kJ
The correct thermodynamic conditions for the spontaneous reaction at all temperature is
The vapour density of N2O4 at a certain temperature is 30. What is the % dissociation of N2O4 at this temperature?