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NEET Chemistry MCQ
Thermodynamics Mcq Neet Chemistry
Quiz 1
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Q.1
All reactions with chemical dissociation are ... [ MP PMT 1990]
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a) reversible
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b) reversible and endothermic
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c) exothermic
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d) reversible or irreversible and endothermic or exothermic
Explanation
Answer: (b)
Q.2
When water is added to quick lime, the reaction is .....[ MP PMT 1995]
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a) explosive
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b) endothermic
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c) exothermic
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d) photochemical
Explanation
Answer: (c)
Q.3
Identify the intensive quantity from the following ... [ IIT 1993]
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a) Enthalpy and temperature
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b) Volume and temperature
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c) Enthalpy and Volume
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d) Temperature and refractive index
Explanation
Answer: (d)
Q.4
In reversible isothermal process, the change in internal energy is ... [ MP PMT 1993]
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a) zero
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b) positive
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c) negative
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d) none of the above
Explanation
Answer: (a)
Q.5
What is the free energy change , ΔG, when 1.0 mole of water at 100°C and 1atm pressure is converted into steam at 100°C and 1atm pressure? [ MP PMT 1998]
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a) 540 cal
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b) -9800 cal
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c) +9800 cal
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d) 0 cal
Explanation
At equilibrium ΔG=0 Answer: (d)
Q.6
For a spontaneous chemical process, the free energy change is ... [ BHU 1981]
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a) Positive
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b) Negative
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c) Either positive or negative
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d) Zero
Explanation
Answer: (b)
Q.7
Measuring Zeta potential is useful in determining which property of colloidal solution? [ NEET 2020]
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a) Stability of the colloidal particles
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b) Size of the colloidal particles
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c) Viscosity
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d) Solubility
Explanation
Answer: (a)
Q.8
For the reaction, 2Cl(g) → Cl2(g), the correct option is : ... [NEET 2020]
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a) ΔrH <0 and ΔrS > 0
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b) ΔrH < 0 and ΔrS < 0
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c) ΔrH > 0 and ΔrS > 0
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d) ΔrH > 0 and ΔrS < 0
Explanation
Answer: (b)
Q.9
Under isothermal condition, a gas at 300 K expands from 0.1 L to 0.25 L against a constant external pressure of 2 bar. The work done by the gas is ... [NEET 2019] (Given that 1 L bar = 100 J)
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a) –30 J
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b) 5 kJ
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c) 25 J
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d) 30 J
Explanation
Answer: (a)
Q.10
For an ideal solution, the correct option is : ... [NEET 2019]
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a) Δmix S = 0 at constant T and P
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b) Δmix V ≠ 0 at constant T and P
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c) Δmix H = 0 at constant T and P
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d) Δmix G = 0 at constant T and P
Explanation
Answer: (c)
Q.11
n which case change in entropy is negative? [NEET 2019]
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a) Evaporation of water
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b) Expansion of a gas at constant temperature
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c) Sublimation of solid to gas
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d) 2H(g) → H2(g)
Explanation
Answer: (d)
Q.12
Hydrolysis of sucrose is given by the following reaction. Sucrose + H2 O ⇋ Glucose + Fructose If the equilibrium constant (KC) is 2 × 1013 at 300 K, the value of ΔrGθ at the same temperature will be : .... [NEET 2020]
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a) 8.314 J mol-11K-1 × 300 K × ln(3 × 1013)
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b) –8.314 J mol-11K-1 ×300K × ln(4 × 1013)
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c) –8.314 J mol-11K-1 × 300 K × ln(2 × 1013)
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d) 8.314 J mol-11K-1 × 300 K × ln(2 × 1013)
Explanation
Answer: (c)
Q.13
The bond dissociation energies of X2, Y2 and XY are in the ratio of 1 : 0·5 :ΔH for the formation of XY is – 200 kJ mol-The bond dissociation energy of X2 will be
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a) 800 kJ mol-1
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b) 100 kJ mol-1
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c) 200 kJ mol-1
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d) 400 kJ mol-1
Explanation
Answer: (a)
Q.14
The standard molar heat of formation of ethane, CO2 and water(l) are respectively -21.1 , -94.1 and -68.3 kcal. The standard molar heat of combustion of ethane will be ... [ IIT 1986]
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a) -372 kcal
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b) 162 kcal
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c) -240 kcal
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d) 183. kcal
Explanation
C2H6 + (7/2) O2 → 2CO2 + 3H2O ΔH=[2 ΔH(CO2) + 3ΔH2O)] - [ ΔH (C2H6) + (7/2)ΔH(O2)] =[ 2(-94.1) +3 (-68.3)] - [ -21.1 +0]=-372 kcalAnswer: (a)
Q.15
Heat of neutralisation of strong acid by a strong base is a constant value because .. [ KCET 1984]
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a) salt formed does not hydrolyse
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b) only H+ and OH- ion react in every case
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c) the strong base and strong acid react completely
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d) the strong base and strong acid react in aqueous solution
Explanation
Answer: (b)
Q.16
The decreasing order of calorific values is .. [ NCERT 1983]
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a) C2H2 < C4H10 < C3H8 < C2H4
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b) C2H2 < C2H4 < C3H8 < C4H10
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c) C2H4 < C3H8< C4H10 < C2H2
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d) C3H8 < C2H4 < C4H10< C2H2
Explanation
Greater the number of C and H atoms greater the calorific value or greater is the ratio of H/C more is calorific value Answer: (b)
Q.17
Enthalpy of neutralisation of HCl with NaOH is x. The heat evolved when 500ml of 2N HCl are mixed with 250ml of 4N NaOH will be... [ AFMC 2002]
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a) 500 x
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b) 100x
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c) x
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d) 10x
Explanation
500 ml of 2N HCl contains 1 mole HCl 250 ml of 4 N NaOH contains 1 mole of NaOHgiven Enthalpy of neutralization is x / mol Answer: (c)
Q.18
The heat of combustion of rhombic and monoclinic sulphur are respectively 70960 and 71030 calories. What will be the heat of conversion or rhombic sulphur to monoclinic? [ MP PMT 1988]
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a) 70960 calories
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b) 71030 calories
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c) -70 calories
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d) +70 calories
Explanation
given (i) S(rhombic) + O2 → SO2 ΔH=70960 caloriesS(monoclinic) + O2 → SO2 ΔH=71030 calories Aim S(rhombic) → S(monoclinic) Eq(1) - eq(2) gives the required result Answer: (c)
Q.19
One mole of an ideal gas is allowed to expand reversibly and adiabatically from a temperature of 27°C. If the work done during the process is 3kJ, the final temperature will be equal to ... [ KCET 2000] (Cv=20J/K)
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a) 450 K
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b) 100 K
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c) 26.85 K
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d) 295 K
Explanation
Work done, one mole, adiabatic reversible W=Cv × ( Tf - Ti)3000=20 ×( Tf - 300 ) Tf=150 KAnswer: (a)
Q.20
For which reaction from the following, ΔS will be maximum? [ AIIMS 1983]
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a) Ca(s) + ½O2(g) → CaO(s)
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b) CaCO3(s) → CaO(s) + CO2(g)
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c) C + O2(g) → CO2(g)
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d) N2(g) + O2 → 2NO(g)
Explanation
In option(b), solid changes into gas. Hence ΔS is maximum Answer: (b)
Q.21
The process of evaporation of a liquid is accompanied by ... [ NCERT 1983]
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a) decrease in entropy
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b) decrease in entropy
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c) no change in free energy
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d) increase in entropy
Explanation
randomness increases, entropy increases Answer: (d)
Q.22
Under the same conditions how many ml of 1M KOH and 0.5M H2SO4 solutions, respectively, when mixed to form a total volume of 100 ml. produce the highest rise in temperature? [ IIT 1993]
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a) 67, 33
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b) 33, 67
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c) 40, 60
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d) 50, 50
Explanation
Basicity of sulphuric acid is two. Thus 50 ml of each will neutralise and volume will be 100 ml Answer: (d)
Q.23
ΔHcombustion of a compound is .. [ Pb.PMT 1985]
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a) positive
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b) negative
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c) zero
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d) positive or negative
Explanation
When a substance undergoes combustion it releases energy. Combustion is always exothermic, the enthalpy change for the reaction is negative, ΔH has a negative sign. Answer: (b)
Q.24
The difference between heat of reaction at constant pressure and constant volume for the reaction 2C6H6 + 15 O2 → 12CO2(g) + 6H2O(l) at 25°C in kJ is ..[IIT 1991]
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a) -7.43
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b) +3.72
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c) -3.72
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d) 7.43
Explanation
heat of reaction at constant pressure=ΔH heat of reaction at constant volume=Δ E ΔH - ΔE=ΔngRTΔng=12 -15=-3 Substituting value of K and T and Δng in above equationΔH - ΔE=-7.43 kJAnswer: (a)
Q.25
The free energy change for a reversible reaction at equilibrium is [ Pb. CET 1991]
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a) zero
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b) small positive
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c) small negative
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d) large positive
Explanation
for equilibrium ΔG=0 Answer: (a)
Q.26
Calculate the free energy change for the following reaction at 300K2CuO(s) → Cu2O(s) + ½O2(g)Given ΔH=145.6 kJ/molΔS=116 JK-1mol-1
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a) 110.8 kJ/mol
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b) 21.5 kJ/mol
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c) 55.4 kJ/mol
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d) 145.6 kJ/mol
Explanation
Answer: (a)
Q.27
Which has maximum calorific value? [ AFMC 1988]
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a) Fat
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b) Protein
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c) carbohydrate
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d) Amino acid
Explanation
Answer: (a)
Q.28
Heat of neutralisation for the reactionNaOH + HCl → NaCl + H2O is 57.1 kJ/mol. What will be the heat released when 0.25 mole of NaOH reacts with 0.25 mole of HCl? ... [ CPMT 1990]
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a) 22.5 kJ/mol
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b) 57.1 kJ/mol
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c) 14.3 kJ/mol
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d) 28.6 kJ/mol
Explanation
Heat of nutralisation is 57.1 kJ/mol In given reaction is for 0.25 moleHeat of nutralisation=0.25×57.1=14.3 kJ/molAnswer: (c)
Q.29
Which of the following statement is correct about heat of combustion? .. [ Bihar CEE 1992]
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a) It may be exothermic in some cases and endothermic in other cases
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b) It is applicable to gaseous substances only
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c) it is always an exothermic reaction
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d) Its value does not change with temperature
Explanation
Answer: (c)
Q.30
Heat of transfer is the heat evolved or absorbed when a substance is converted from ... [ KCET 1984]
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a) solid to liquid
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b) solid to vapour
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c) liquid to vapour
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d) one allotropic form to another allotropic form
Explanation
Answer: (d)
0 h : 0 m : 1 s
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