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CBSE Questions for Class 11 Medical Chemistry Thermodynamics Quiz 14 - MCQExams.com

When two mole of an ideal gas (Cp.m=52R) heated from 300K to 600K at constant pressure. The change in entropy of gas (ΔS) is:
  • 32Rln2
  • 32Rln2
  • 5Rln2
  • 52Rln2
For the reactionAB+C. At equilibrium, the concentration of A is 1×103M ,B is 0.15M and C is 0.05M. The Go for the reaction A at 27oC will be
  • 5kJ/mol
  • 17.3kJ/mol
  • 11.2kJ/mol
  • none of these
Which of the following is/are correct ?
  • ΔH=ΔU+Δ (PV) when P and V both changes
  • ΔH=ΔU+PΔV when pressure is constant
  • ΔH=ΔU+VΔP when volume is constant
  • all are correct
Which of the following processes are spontaneous
  • Melting of ice at 2 atm and 273K
  • Melting point of ice at 1/2 atm and273K
  • Boiling of water at 1/2 atm and 373K
  • Boiling of water at 2 atm and 373K
For a reaction. A(g)A(l);ΔH=3RT. The correct statement for the reaction is:
  • |ΔH|>|ΔU|
  • ΔH=ΔU0
  • |ΔH|<|ΔU|
  • ΔH=ΔU=0
For the spontaneous process 2F(g)F2(g), the sign of ΔH and ΔS respectively are?
  • +ve, -ve
  • +ve, +ve
  • -ve, -ve
  • -ve, +ve
The favourable conditions for a spontaneous reaction are:
  • TΔS>ΔH,ΔH=+ve,ΔS=+ve
  • TΔS>ΔH,ΔH=+ve,ΔS=ve
  • TΔS=ΔH,ΔH=+ve,ΔS=ve
  • TΔS=ΔH,ΔH=+ve,ΔS=+ve
For a reaction R1,ΔG=xKJmol1. For a reaction R2,ΔG=y KJmol1. Reaction R1 is non spontaneous but along with R2 it is spontaneous. This means that:
  • x is ve, y is +ve but in magnitude x>y
  • x is ve, y is +ve but in magnitude y>x
  • Both x and y are ve but not equal
  • Both x and y are +ve but not equal
Which of the following conditions make the process non spontaneous at all temperatures. 
  • ΔH=+ve;ΔS=ve
  • ΔH=ve;ΔS=+ve
  • ΔH=+ve;ΔS=+ve
  • ΔH=ve;ΔS=ve
Consider the formation of MgO(s). Assume that Ho and So are independent of temperature:
Mg(s)+12O2(g)MgO(s)
 Ho=602kJ/mol, So=108kJ/mol

Calculate G for formation of MgO(s) at 0oC and is the reacion spontaneous or non spontaneous at 0oC?
  • 29,000kJ/mol, spontaneous
  • 29,000kJ/mol, non spontaneous
  • 30,000kJ/mol,  spontaneous
  • 30,000kJ/mol, non spontaneous
For a spontaneous reaction, the ΔG, equilibrium constant, K and will be respectively:
  • ve,>1
  • +ve,1
  • ve,<1
  • ve.1
For a gaseous reaction,
A(g)+3B(g)3C(g)+3D(g)

ΔE is 17kcal at 27oC, assuming R=2cal K1 mol1, the value of ΔH for the above reaction is:
  • 15.8kcal
  • 18.2kcal
  • 20.0kcal
  • 16.4kcal
ΔGo of Cu+(aq) and Cu2+(aq) respectively are +50 and +66kJ/mole. Value of (ΔHoTΔSo) for Cu+(aq)Cu2+(aq) in kilo joules is?
  • 16
  • +116
  • 116
  • +16
Which plot represents for an exothermic reaction:
Consider the reaction:

4NO2(g)+O2(g)2N2O5(g);ΔrH=111kJ 

If N2O5(s) is formed instead of N2O5(g) in the above reaction, then ΔrH value will be: 
[Given, ΔH of sublimation for N2O5 is 54kJmol1]
  • +54 kJ
  • +219 kJ
  • 219 kJ
  • 165 kJ
ΔSsurroundings=+959.1JK1mol1
ΔSsystem=163.1JK1mol1. Then process is?
  • Spontaneous
  • Non spontaneous
  • At equilibrium
  • Cannot be predicted from the information
ΔS for 4Fe(s)+3O2(s)2Fe2O3(s) is 550J/mol/K. The process is found to be spontaneous even at 298K because  (ΔH=1650kJ)
  • ΔStotal=2000J
  • ΔStotal=+1650J
  • ΔStotal=+4980J
  • ΔStotal=4980J
In which of the following case entropy decreases-
  • Solid changing to liquid
  • Expansion of a gas
  • Crystals dissolve
  • Polymerisation
Ethyl chloride (C2H5Cl) is prepared by reaction of ethylene with hydrogen cloride:
C2H4(g)+Hcl(g)C2H5Cl(g); ΔH=72.3kJ
What is the value of ΔE (in kJ), if 70g of ethylene and 73g of HCl are allowed to react at 300K
  • 69.8
  • 180.75
  • 174.5
  • 139.6
Consider the following processes H(KJ/mol)
12AB                                +150
3B2C+D                      125
E+AD                          +350
For B+DE+2C,            H will be :
  • 325kJ/mol
  • 525kJ/mol
  • 175kJ/mol
  • 325kJ/mol
An equilibrium reaction X+YW+Z,H=+ve is spontaneous in the forward direction. Then corresponding sign of G and S should be respectively:
  • +ve, -ve
  • -ve , +ve
  • +ve , +ve
  • -ve , -ve
Rank the following substances in order of decreasing heat of combusion (maximum minimum). 
1147050_fa87452fe2754c599cafdc322fc18c1d.PNG
  • 1>2>4>3
  • 3>4>2>1
  • 2>4>1>3
  • 1>3>2>4
In an insulated container 1 mole of a liquid. molar volume 100 ml at 1 bar. Liquid is steeply taken to 100 bar, when volume of liquid decreases by 1 ml. Find ΔH for the process.
  • 7900 bar mL
  • 8900 bar mL
  • 9900 bar mL
  • 10900 bar mL
the above reaction was carried out at 300 K in a bomb calorimeter. The heat released was 743 kJ/mol. The value of H300K for this reaction would be:
1150768_6af018e7e93c4d95b441795c6f52c312.jpg
  • -740.5 kJ/mol
  • -741.75 kJ/mol
  • -743.0 kJ/mol
  • -744.25 kJ/mol
For the reactionAB+C At the equilibrium, the concentration of A is 1×103M  is B is 0.15M and C is 0.05M. The Go for the reaction at 27oC  will be
  • 5kJ/mol
  • 17.36kJ/mol
  • 11.2kJ/mol
  • 10.1kJ/mol
Given  the following data:
Substance    ΔH(KJ/mol)     S(J/mol K)     ΔG(KJ/mol) 
FeO(s)            -266.3               57.49             -245.12  
C(Graphite)      0                     5.74                    0
Fe(s)                 0                     27.28                  0
CO(g)                -110.5              197.6                -137.15
Determine at what temperature the following reaction is spontaneous ?
FeO(s) + C(Graphite)Fe(s) + CO(g)
  • 289 K
  • 668 K
  • 966 K
  • Go is  + ve. hence the reaction will never be spontaneous
For the process,CO2(s)CO2(g) 
  • Both ΔH and ΔS are negative 
  • ΔH is negative and ΔS is positive
  • ΔH is +Ve and ΔS is negative
  • Both ΔH and ΔS are positive
Spontaneity may be observed in following conditions
  • H = -ve, S = +ve
  • H = +ve, S = +ve
  • H = -ve, S = -ve
  • All of these
Using the data provided, calculate the multiple bond energy (kJ / mol) of a C=C bond in C2H2.  (Take the bond energy of a C-H bond as 350 kJ / mol)

2C(s)+H2(g)C2H2(g) ΔH=225kJ/mol 
2C(s)2C(g);ΔH=1410kJmol1
H2(g)2H(g);ΔH=330kJmol1
  • 1165
  • 837
  • 865
  • 815
In a reaction, the change in entropy is given as 2.4 cal/K and the change in Gibbs free energy is given as 3.4 kcal, calculate the change in heat at the temperature of 20-degree centigrade?
  • 3.4 kcal
  • 3.4 cal
  • 3.4 kJ
  • 3.4 J
For the reaction between CO2 and graphite
CO2(g)+C(s)2CO(g)
ΔH=170.0KJandΔs=170JK1. The reaction is spontaneous at
  • 298 K
  • 500 K
  • 900 K
  • none of the above
An endothermic reaction is spontaneous if 
  • ΔH>TΔS
  • ΔH<TΔS
  • ΔH=TΔS
  • TΔS=0
For the reaction,AB,ΔH=+ve,ΔS=ve This reaction is 
  • non-spontaneous at all temperature
  • non-spontaneous at low temperature
  • non-spontaneous at high temperature
  • spontaneous at high temperature
For the reaction X2Y4(l)2XY2(g) at 300 K the values of ΔU and ΔS are 2kcal and 20calK1 respectively. The value of ΔG for the reaction is:
  • -3400 cal
  • 3400 cal
  • 2000 cal
  • -2800 cal
The reaction 2A(g)A2(g), will be spontaneous 
  • At high temperature
  • At low temperature
  • At all temperature
  • Never at any temperature
The correct thermodynamic conditions for the spontaneous reaction at all temperature is:
  • ΔH<0 and ΔS=0
  • ΔH>0 and ΔS<0
  • ΔH<0 and ΔS>0
  • ΔH<0 and ΔS<0
Consider the following processes:
12AB:H=150
3B2C+D:H=125
E+A2D=350
For B+D E+2C,H will be:

  • 325 kJ/mol
  • 525 kJ/mol
  • -175 kJ/mol
  • -325 kJ/mol
The difference between heat of reaction at pressure and constant volume for the reaction, CH2=CH2(g)+3O2(g)2CO2(g)+2H2O(l) at 300 K is?
  • 5.87 kJ
  • -4.99 kJ
  • 6.89 kJ
  • -7.25 kJ
Given that Zn+1/2O2ZnO+35.25kJ.HgOHg+1/2O2+9.11kJ. The heat of the reaction Zn+HgOZnO+Hg is
  • -26.14kJ
  • 44.39kJ
  • -44.39kJ
  • 26.14kJ
What is the free energy change G, when 1.0 mole of water at 100oC and 1 atm pressure is converted steam at 100oC and 1  atm pressure:-
  • +540 cal
  • -9800 cal
  • +9800 cal
  • 0 cal
500 J of heat was supplied to a system at constant volume.It resulted in the increase of temperature of the system from 20oC to 25oC .What is the change in internal energy of the system?
  • +8.43 J
  • +43 J
  • +458.43 J
  • +580.43 J
The P - V diagram of a system undergoing a thermodynamic process is shown in figure. Work done by the system in going from ABC is 30 J and 40 J heat is given to the system. The change in internal energy of the gas if the gas is directly taken from A to C  is 
1220371_d045802094ee4bc1a8c4acc68a17ce7f.png
  • 10 J
  • 70 J
  • 84 J
  • 134 J
2Al2(s)4Al(s)+3O2(g),G=+138 kcal considering the contributing of entropy to the spontaneity of this reaction, the reaction is________And entropy of the system_______.
  • Spontaneous increase
  • Spontaneous decrease
  • non-Spontaneous, increase
  • non-Spontaneous decrease
For reaction AB, ΔH and ΔS are positive. the most favourable condition of spontaneous process.
  • low temperature
  • high temperature
  • high concentration
  • very low temperature
The Gibb's energy for the decomposition of Al2O3 at 500oC is as follows:
2/3Al2O34/3Al+O2rG=+966kJmol1
The potential difference needed for electrolytic reduction of  Al2O3 at 500oC is at least
  • 5.0 V
  • 4.5 V
  • 3.0 V
  • 2.5 V
Dextrorotatory  α  -pinene has a specific rotation  [α]20D=+51.3.  A sample of  αpinene  containing both the enantiomers was found to have a specific rotation value  [α]20D=+30.8.  The percentages of the  (+)  and  ()  enantiomers present in the sample are, respectively.
  • 70% and 30%
  • 80% and 20%
  • 20% and 80%
  • 60% and 40%
NH3(g)+3Cl2\vboxto.5ex\vssNCl4(g)+3HCl:ΔH1N2(g)+3H2(g)\vboxto.5ex\vss2NH3(g):ΔH2H2(g)+Cl2(g)\vboxto.5ex\vss2HCl(g):ΔH3
The heat of formation of NCl4 in the terms of ΔH1,ΔH2,ΔH3 is:
  • ΔH1=ΔH1+ΔH2232ΔH3
  • ΔH1=ΔH1+ΔH2232ΔH3
  • ΔH1=ΔH1ΔH22+32ΔH3
  • none of these
An ideal gas expands according to the law P2V= constant. The internal energy of the gas
  • Increases continuously
  • Decreases continuously
  • Remain constant
  • First increases and then decreases
In which of the following ionic compounds, ΔHf is negative only due to lattice energy: 
(i) NaF       (ii) MgO        (iii)Li2N      (iv)Na2S
  • Only (iv)
  • Only (iii) and (iv)
  • Only (ii), (iii), (iv)
  • All of these
When a bottle of perfume is opened, odorous molecules mix with air and slowly diffuse throughout the entire room. The incorrect fact about the process is:
  • G=Ve
  • H0
  • S=Ve
  • S=+ve
0:0:1


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