Question 1: Palette 1/86

NEET 2026 MCQ

Consider the following reaction :

$ \begin{aligned} & 2 \mathrm{~A}(\mathrm{~g})+\mathrm{B}(\mathrm{~g}) \rightarrow 2 \mathrm{D}(\mathrm{~g}) \\ & \Delta \mathrm{U}^{\ominus}=-10 \mathrm{~kJ} \mathrm{~mol}^{-1} \text { and } \Delta \mathrm{S}^{\ominus}=-44 \mathrm{JK}^{-1} \text { at } 298 \mathrm{~K} . \end{aligned} $

Identify the correct option with $\Delta \mathrm{G}^{\ominus}$ for the reaction and spontaneity of the reaction at 298 K .

(Given : $\mathrm{R}=8.31 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ )

A

$-1.635 \mathrm{~kJ} \mathrm{~mol}^{-1}$, spontaneous

B

$-0.63568 \mathrm{~kJ} \mathrm{~mol}^{-1}$, spontaneous

C

$+0.63568 \mathrm{~kJ} \mathrm{~mol}^{-1}$, non-spontaneous

D

$+1.635 \mathrm{~kJ} \mathrm{~mol}^{-1}$, non-spontaneous

Question 2: Palette 2/86

NEET 2026 MCQ

At a certain temperature, $\mathrm{T}(\mathrm{K})$, during a process, 500 J is absorbed by the system and work of 200 J is done by the system. Then change in internal energy of the system is :

A

400 J

B

300 J

C

700 J

D

500 J

Question 3: Palette 3/86

NEET 2026 MCQ

Two moles of an ideal gas undergo free expansion from 10 L to 100 L at 300 K . The values of $\Delta \mathrm{S}_{\text {system }}$ and $\Delta \mathrm{S}_{\text {surroundings }}$ are

( $R$ is universal gas constant)

A

$\Delta \mathrm{S}_{\text {system }}=4.606 \mathrm{R} ; \Delta \mathrm{S}_{\text {surroundings }}=0$

B

$\Delta \mathrm{S}_{\text {system }}=0 ; \Delta \mathrm{S}_{\text {surroundings }}=0$

C

$\Delta \mathrm{S}_{\text {system }}=4.606 \mathrm{R} ; \Delta \mathrm{S}_{\text {surroundings }}=-4.606 \mathrm{R}$

D

$\Delta \mathrm{S}_{\text {system }}=0 ; \Delta \mathrm{S}_{\text {surroundings }}=4.606 \mathrm{R}$

Question 4: Palette 4/86

NEET 2026 MCQ

$ \text { Consider the reversible processes for } 1.0 \mathrm{~mol} \text { of an ideal gas as shown in the figure. } $

$w_1, w_2, w_3$ and $w_4$ represent work done (in calories) in the processes $1,2,3$ and 4 , respectively; $\Delta U_2$ and $\Delta U_4$ are changes in the internal energy for the processes 2 and 4, respectively.

[use $\mathrm{R}=2 \mathrm{cal} \mathrm{K}^{-1} \mathrm{~mol}^{-1}$ ]

The correct option is

A

$\mathrm{w}_1+\mathrm{w}_2+\mathrm{w}_3+\mathrm{w}_4=0$

B

$\mathrm{w}_1+\mathrm{w}_3=-2 \mathrm{~T}_1 \ln \frac{\mathrm{~V}_2}{\mathrm{~V}_1}-2 \mathrm{~T}_2 \ln \frac{\mathrm{~V}_4}{\mathrm{~V}_3}$

C

$\mathrm{w}_2+\mathrm{w}_4=\Delta \mathrm{U}_2-\Delta \mathrm{U}_4$

D

$\mathrm{w}_1+\mathrm{w}_2=2 \mathrm{~T}_1 \ln \frac{\mathrm{~V}_2}{\mathrm{~V}_1}$

Question 5: Palette 5/86

NEET 2026 MCQ

A protein undergoes reversible thermal denaturation from its initial state $\mathbf{N}$ to denatured state $\mathbf{D}$ according to $\mathbf{N} \rightleftharpoons \mathbf{D}$. At $60^{\circ} \mathrm{C}$, the concentrations of both $\mathbf{N}$ and $\mathbf{D}$ are equal at equilibrium, and the standard enthalpy change of denaturation is $666 \mathrm{~kJ} \mathrm{~mol}^{-1}$. The standard entropy change $\Delta \mathrm{S}^{\circ}$ in $\mathrm{kJ} \mathrm{K}^{-1} \mathrm{~mol}^{-1}$ ) of the protein upon denaturation at $60^{\circ} \mathrm{C}$ is closest to

A

11.1

B

2.0

C

2000.0

D

333.0

Question 6: Palette 6/86

NEET 2025 MCQ

The standard heat of formation, in $\mathrm{kcal} / \mathrm{mol}$ of $\mathrm{Ba}^{2+}$ is : [Given : standard heat of formation of $\mathrm{SO}_4^{2-}$ ion $(\mathrm{aq})=-216 \mathrm{kcal} / \mathrm{mol}$, standard heat of crystallisation of $\mathrm{BaSO}_4(\mathrm{~s})=-4.5 \mathrm{kcal} / \mathrm{mol}$, standard heat of formation of $\left.\mathrm{BaSO}_4(\mathrm{~s})=-349 \mathrm{kcal} / \mathrm{mol}\right]$

A

+133.0

B

+220.5

C

$-$128.5

D

$-$133.0

Question 7: Palette 7/86

NEET 2025 MCQ

$\mathrm{C}(\mathrm{s})+2 \mathrm{H}_2(\mathrm{~g}) \rightarrow \mathrm{CH}_4(\mathrm{~g}) ; \Delta \mathrm{H}=-74.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$. Which of the following diagrams gives an accurate representation of the above reaction? [ $\mathrm{R} \rightarrow$ reactants; $\mathrm{P} \rightarrow$ products]

A

B

C

D

Question 8: Palette 8/86

NEET 2024 MCQ

Choose the correct statement for the work done in the expansion and heat absorbed or released when 5 litres of an ideal gas at 10 atmospheric pressure isothermally expands into vacuum until volume is 15 litres :

A

Both the heat and work done will be greater than zero

B

Heat absorbed will be less than zero and work done will be positive

C

Work done will be zero and heat will also be zero

D

Work done will be greater than zero and heat will remain zero

Question 9: Palette 9/86

NEET 2024 MCQ

For an endothermic reaction:

(A) $\mathrm{q}_{\mathrm{p}}$ is negative.

(B) $\Delta_{\mathrm{r}} \mathrm{H}$ is positive.

(C) $\Delta_r \mathrm{H}$ is negative.

(D) $\mathrm{q}_{\mathrm{p}}$ is positive.

Choose the correct answer from the options given below:

A

B and D

B

C and D

C

A and B

D

A and C

Question 10: Palette 10/86

NEET 2024 MCQ

For the following reaction at $300 \mathrm{~K}$

$\mathrm{A}_2(\mathrm{~g})+3 \mathrm{~B}_2(\mathrm{~g}) \rightarrow 2 \mathrm{AB}_3(\mathrm{~g})$

the enthalpy change is $+15 \mathrm{~kJ}$, then the internal energy change is :

A

$19988.4 \mathrm{~J}$

B

$200 \mathrm{~J}$

C

$1999 \mathrm{~J}$

D

$1.9988 \mathrm{~kJ}$

Question 11: Palette 11/86

NEET 2024 MCQ

In which of the following processes entropy increases?

A. A liquid evaporates to vapour.

B. Temperature of a crystalline solid lowered from $130 \mathrm{~K}$ to $0 \mathrm{~K}$.

C. $2 \mathrm{NaHCO}_{3(\mathrm{~s})} \rightarrow \mathrm{Na}_2 \mathrm{CO}_{3(\mathrm{~s})}+\mathrm{CO}_{2(\mathrm{~g})}+\mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}$

D. $\mathrm{Cl}_{2(g)} \rightarrow 2 \mathrm{Cl}_{(g)}$

Choose the correct answer from the options given below:

A

A and C

B

A, B and D

C

A, C and D

D

C and D

Question 12: Palette 12/86

NEET 2024 MCQ

Match List I with List II.

	List I (Process)		List II (Conditions)
A.	Isothermal process	I.	No heat exchange
B.	Isochoric process	II.	Carried out at constant temperature
C.	Isobaric process	III.	Carried out at constant volume
D.	Adiabatic process	IV.	Carried out at constant pressure

Choose the correct answer from the options given below:

A

A-IV, B-III, C-II, D-I

B

A-IV, B-II, C-III, D-I

C

A-I, B-II, C-III, D-IV

D

A-II, B-III, C-IV, D-I

Question 13: Palette 13/86

NEET 2024 MCQ

The work done during reversible isothermal expansion of one mole of hydrogen gas at $25^{\circ} \mathrm{C}$ from pressure of 20 atmosphere to 10 atmosphere is (Given $\mathrm{R}=2.0 \mathrm{~cal} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$)

A

0 calorie

B

$-$413.14 calories

C

413.14 calories

D

100 calories

Question 14: Palette 14/86

NEET 2023 MCQ

Consider the following reaction :-

$2 \mathrm{H}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{H}_2 \mathrm{O}(\mathrm{g}) \Delta_{\mathrm{r}} \mathrm{H}^{\circ}=-483.64 \mathrm{~kJ} \text {. }$

What is the enthalpy change for decomposition of one mole of water? (Choose the right option).

A

120.9 kJ

B

241.82 kJ

C

18 kJ

D

100 kJ

Question 15: Palette 15/86

NEET 2023 MCQ

The equilibrium concentrations of the species in the reaction $\mathrm{A}+\mathrm{B} \rightleftharpoons \mathrm{C}+\mathrm{D}$ are $2,3,10$ and $6 \mathrm{~mol}$ $\mathrm{L}^{-1}$, respectively at $300 \mathrm{~K} . \Delta \mathrm{G}^{0}$ for the reaction is $(\mathrm{R}=2 \mathrm{cal} / \mathrm{mol} ~\mathrm{K})$

A

$-137.26 ~\mathrm{cal}$

B

$-1381.80 ~\mathrm{cal}$

C

$-13.73 ~\mathrm{cal}$

D

$1372.60 ~\mathrm{cal}$

Question 16: Palette 16/86

NEET 2023 MCQ

Which amongst the following options is the correct relation between change in enthalpy and change in internal energy?

A

$\Delta \mathrm{H}=\Delta \mathrm{U}+\Delta \mathrm{n_g R T}$

B

$\Delta \mathrm{H}-\Delta \mathrm{U}=-\Delta \mathrm{nRT}$

C

$\Delta \mathrm{H}+\Delta \mathrm{U}=\Delta \mathrm{nR}$

D

$\Delta \mathrm{H}=\Delta \mathrm{U}-\Delta \mathrm{n_g R T}$

Question 17: Palette 17/86

NEET 2022 MCQ

One mole of an ideal gas at 300 K is expanded isothermally from 1 L to 10 L volume. $\Delta$U for this process is :

(Use R = 8.314 J k^$-$1 mol^$-$1)

A

0 J

B

1260 J

C

2520 J

D

5040 J

Question 18: Palette 18/86

NEET 2022 MCQ

A vessel contains 3.2 g of dioxygen gas at STP (273.15 K and 1 atm pressure). The gas is now transferred to another vessel at constant temperature, where pressure becomes one third of the original pressure. The volume of new vessel in L is : (Given : molar volume at STP is 22.4 L)

A

67.2

B

6.72

C

2.24

D

22.4

Question 19: Palette 19/86

NEET 2022 MCQ

Which of the following p-V curve represents maximum work done?

A

B

C

D

Question 20: Palette 20/86

NEET 2021 MCQ

Which one among the following is the correct option for right relationship between C_P and C_V for one mole of ideal gas?

A

C_V = RC_P

B

C_P + C_V = R

C

C_P $-$ C_V = R

D

C_P = RC_V

Question 21: Palette 21/86

NEET 2021 MCQ

For irreversible expansion of an ideal gas under isothermal condition, the correct option is :

A

$\Delta$U $\ne$ 0, $\Delta$S_total = 0

B

$\Delta$U = 0, $\Delta$S_total = 0

C

$\Delta$U $\ne$ 0, $\Delta$S_total $\ne$ 0

D

$\Delta$U = 0, $\Delta$S_total $\ne$ 0

Question 22: Palette 22/86

NEET 2020 MCQ

Hydrolysis of sucrose is given by the following reaction.
Sucrose + H₂O ⇌ Glucose + Fructose
If the equilibrium constant (K_c) is 2 $ \times $ 10¹³ at 800 K, the value of $\Delta r{G^\Theta }$ at the same temperature will be :

A

8.314 J $mo{l^{ - 1}}{K^{ - 1}} \times 300K \times In(2 \times {10^{13}})$

B

8.314 J $mo{l^{ - 1}}{K^{ - 1}} \times 300K \times In(3 \times {10^{13}})$

C

$ - $ 8.314 J $mo{l^{ - 1}}{K^{ - 1}} \times 300K \times In(4 \times {10^{13}})$

D

-8.314 J $mo{l^{ - 1}}{K^{ - 1}} \times 300K \times In(2 \times {10^{13}})$

Question 23: Palette 23/86

NEET 2020 MCQ

For the reaction, 2Cl(g) $ \to $ Cl₂(g), the correct option is :

A

${\Delta _r}H > 0$ and ${\Delta _r}S < 0$

B

${\Delta _r}H < 0$ and ${\Delta _r}S > 0$

C

${\Delta _r}H < 0$ and ${\Delta _r}S < 0$

D

${\Delta _r}H > 0$ and ${\Delta _r}S > 0$

Question 24: Palette 24/86

NEET 2020 MCQ

The correct option for free expansion of an ideal gas under adiabatic condition is :

A

q = 0, $\Delta $ T < 0 and w > 0

B

q < 0, $\Delta $ T = 0 and w = 0

C

q > 0, $\Delta $ T > 0 and w > 0

D

q = 0, $\Delta $ T = 0 and w = 0

Question 25: Palette 25/86

NEET 2019 MCQ

In which case change in entropy is negative?

A

Sublimation of solid to gas

B

2H(g) $ \to $ H₂(g)

C

Evaporation of water

D

Expansion of a gas at temperature

Question 26: Palette 26/86

NEET 2019 MCQ

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 [Given that 1 L bar = 100 J]

A

25 J

B

30 J

C

-30 J

D

5 kJ

Question 27: Palette 27/86

NEET 2018 MCQ

The bond dissociation energies of X₂ , Y₂ and XY are in the ratio of 1 : 0.5 : 1. $\Delta $H for the formation of XY is –200 kJ mol^–1. The bond dissociation energy of X₂ will be

A

800 kJ mol^–1

B

200 kJ mol^–1

C

400 kJ mol^–1

D

100 kJ mol^–1

Question 28: Palette 28/86

NEET 2017 MCQ

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy $\Delta $U of the gas in joules will be

A

$-$ 500 J

B

$-$ 505 J

C

+ 505 J

D

1136.25 J

Question 29: Palette 29/86

NEET 2017 MCQ

For a given reaction, $\Delta $H = 35.5 kJ mol^$-$1 and $\Delta $S = 83.6 J K^$-$1 mol^$-$1. The reaction is spontaneous at (Assume that $\Delta $H and $\Delta $S do not vary with temperature.)

A

T > 425 K

B

all temperatures

C

T > 298 K

D

T < 425 K

Question 30: Palette 30/86

NEET 2016 MCQ

For a sample of perfect gas when its pressure is changed isothermally from p_i to p_f, the entropy change is given by

A

$\Delta S = nR\,\ln \left( {{{{p_f}} \over {{p_i}}}} \right)$

B

$\Delta S = nR\,\ln \left( {{{{p_i}} \over {{p_f}}}} \right)$

C

$\Delta S = nRT\,\ln \left( {{{{p_f}} \over {{p_i}}}} \right)$

D

$\Delta S = RT\,\ln \left( {{{{p_i}} \over {{p_f}}}} \right)$

Question 31: Palette 31/86

NEET 2016 MSQ

The correct thermodynamic conditions for the spontaneous reaction at all temperatures is

A

$\Delta $H < 0 and $\Delta $S > 0

B

$\Delta $H < 0 and $\Delta $S < 0

C

$\Delta $H < 0 and $\Delta $S = 0

D

$\Delta $H > 0 and $\Delta $S < 0

Question 32: Palette 32/86

NEET 2015 MCQ

The heat of combination of carbon to CO₂ is $-$393.5 kJ/mol. The heat released upon formation of 35.2 g of CO₂ from carbon and oxygen gas is

A

+ 315 kJ

B

$-$630 kJ

C

$-$ 3.15 kJ

D

$-$ 315 kJ

Question 33: Palette 33/86

NEET 2014 MCQ

For the reaction, ${X_2}{O_{4\left( l \right)}}\,\, \to \,\,2X{O_{2(g)}}$

$\Delta $U = 2.1 kcal, $\Delta $S = 20 cal K^$-$1 at 300 K

Hence, G is

A

2.7 kcal

B

$-$ 2.7 kcal

C

9.3 kcal

D

$-$ 9.3 kcal

Question 34: Palette 34/86

NEET 2014 MCQ

Which of the following statements is correct for the spontaneous adsorption of a gas?

A

$\Delta $S is negative and, therefore $\Delta $H should be highly positive.

B

$\Delta $S is negative and therefore, $\Delta $H should be highly negative.

C

$\Delta $S is positive and therefore, $\Delta $H should be negative .

D

$\Delta $S is positive and therefore, $\Delta $H should also be highly positive.

Question 35: Palette 35/86

NEET 2013 MCQ

When 5 litres of a gas mixture of methane and propane is perfectly combusted at 0^oC and 1 atmosphere, 16 litres of oxygen at the same temperature and pressure is consumed, The amount of heat released from this combustion in kJ ($\Delta $H_comb. (CH₄) = 890 kJ mol^$-$1, $\Delta $H_comb. (C₃H₈) = 2220 kJ mol^$-$1) is

A

38

B

317

C

477

D

32

Question 36: Palette 36/86

NEET 2013 MCQ

Three thermochemical equations are given below
(i)  C_(graphite) + O_2(g) $ \to $ CO_2(g); $\Delta $_rH^o = x kJ mol^$-$1
(ii)  C_(graphite) + ${1 \over 2}$O_2(g) $ \to $ CO_(g); $\Delta $_rH^o = y kJ mol^$-$1
(iii)  CO_(g) + ${1 \over 2}$O_2(g) $ \to $ CO_2(g); $\Delta $_rH^o = z kJ mol^$-$1
Based on the above equations, find out which of the relationship given below is correct.

A

z = x + y

B

x = y + z

C

y = 2z $-$ x

D

x = y $-$ z

Question 37: Palette 37/86

NEET 2013 MCQ

A reaction having equal energies of activation for forward and reverse reactions has

A

$\Delta $H = 0

B

$\Delta $H = $\Delta $G = $\Delta $S = 0

C

$\Delta $S = 0

D

$\Delta $G = 0

Question 38: Palette 38/86

NEET 2012 MCQ

In which of the following reactions, standard reaction entropy change ($\Delta $S^o) is positive and standard Gibb's energy change ($\Delta $G^o) decreases sharply with increasing temperature ?

A

C_(graphite) + ${1 \over 2}$O_2(g) $ \to $ CO_(g)

B

CO_(g) + ${1 \over 2}$O_2(g) $ \to $ CO_2(g)

C

Mg_(s) + ${1 \over 2}$O_2(g) $ \to $ MgO_(g)

D

${1 \over 2}$C_(graphite) + ${1 \over 2}$O_2(g) $ \to $ ${1 \over 2}$CO_2(g)

Question 39: Palette 39/86

NEET 2012 MCQ

Standard enthalpy of vaporisation $\Delta $_vapH^o for water at 100^oC is 40.66 kJ mol^$-$1. The internal energy of vaporisation of water at 100^oC (in kJ mol^$-$1) is

A

+37.56

B

$-$43.76

C

+ 43.76

D

+ 40.66

Question 40: Palette 40/86

NEET 2012 MCQ

The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0^oC is

A

10.52 cal/(mol K)

B

21.04 cal/(mol K)

C

5.260 cal/(mol K)

D

0.526 cal/(mol K)

Question 41: Palette 41/86

NEET 2011 MCQ

Consider the following processes :

	H (kJ/mol)
1/2A $ \to $ B	+150
3B  $ \to $ 2C + D	-125
E + A  $ \to $ 2D	+350

For B + D $ \to $ E + 2C, $\Delta $H will be

A

525 kJ/mol

B

$-$175 kJ/mol

C

$-$ 325 kJ/mol

D

325 kJ/mol

Question 42: Palette 42/86

NEET 2011 MCQ

If the enthalpy change for the transition of liquid water to steam is 30 kJ mol^$-$1 at 27^oC, the entropy change for the process would be

A

10 J mol^$-$1 K^$-$1

B

1.0 J mol^$-$1 K^$-$1

C

0.1 J mol^$-$1 K^$-$1

D

100 J mol^$-$1 K^$-$1

Question 43: Palette 43/86

NEET 2011 MCQ

Which of the following is correct option for free expansion of an ideal gas under adiabatic condition ?

A

q = 0, $\Delta $T $ \ne $ 0, w = 0

B

q $ \ne $ 0,   $\Delta $T = 0,   w = 0

C

q = 0,   $\Delta $T = 0,   w = 0

D

q = 0,  $\Delta $T < 0, w $ \ne $ 0

Question 44: Palette 44/86

NEET 2011 MCQ

Enthalpy change for the reaction,
4H_(g)  $ \to $  2H_2(g) is $-$869.6 kJ
The dissociation energy of H $-$ H bond is

A

434.8 kJ

B

$-$ 869.6 kJ

C

+ 434.8 kJ

D

+ 217.4 kJ

Question 45: Palette 45/86

NEET 2010 MCQ

Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be

A

infinite

B

3 Joules

C

9 Joules

D

zero

Question 46: Palette 46/86

NEET 2010 MCQ

Match List I (Equations) with List II (Type of processes) and select the correct option.

List I		List II
Equations		Type of processes
A.	Kp > Q	(i)	Non- spontaneous
B.	$\Delta $Go < RT ln Q	(ii)	Equilibrium
C.	Kp = Q	(iii)	Spontaneous and endothermic
D.	T > ${{\Delta H} \over {\Delta S}}$	(iv)	Spontaneous

A

A - (i), B - (ii), C - (iii), D - (iv)

B

A - (iii), B - (iv), C - (ii), D - (i)

C

A - (iv), B - (i), C - (ii), D - (iii)

D

A - (ii), B - (i), C - (iv), D - (iii)

Question 47: Palette 47/86

NEET 2010 MCQ

For vaporization of water at 1 atmospheric pressure, the values of $\Delta $H and $\Delta $S are 40.63 kJ mol^$-$1 and 108.8 J K^$-$1 mol^$-$1, respectively. The temperature when Gibb's energy change ($\Delta $G) for this transformation will be zero, is

A

273.4 K

B

393.4 K

C

373.4 K

D

293.4 K

Question 48: Palette 48/86

NEET 2010 MCQ

The following two reactions are known

Fe₂O_3(s) + 3CO_(g) $ \to $ 2Fe_(s) + 3CO_2(g); $\Delta $H = $-$ 26.8 kJ

FeO_(s) + CO(g) $ \to $  Fe_(s) + CO_2(g); $\Delta $H = $-$ 16.5 kJ

The value of $\Delta $H for the following reaction

Fe₂O_3(s) + CO_(g) $ \to $  2FeO_(s) + CO_2(g) is

A

+ 10.3 kJ

B

$-$ 43.3 kJ

C

$-$ 10.3 kJ

D

+ 6.2 kJ

Question 49: Palette 49/86

NEET 2010 MCQ

Standard entropies of X₂, Y₂ and XY₃ are 60, 40 and 50 J K^$-$1 mol^$-$1 respectively. For the reaction

1/2X₂ + 3/2Y₂ $\rightleftharpoons$ XY₃, $\Delta $H = $-$ 30 kJ,

to be at equilibrium, the temperature should be

A

750 K

B

1000 K

C

1250 K

D

500 K

Question 50: Palette 50/86

NEET 2010 MCQ

For an endothermic reaction, energy of activation is E_a and enthalpy of reaction is $\Delta $H (both of these in kJ/mol). Minimum value of E_a will be

A

less than $\Delta $H

B

equal to $\Delta $H

C

more than $\Delta $H

D

equal to zero

Question 51: Palette 51/86

NEET 2009 MCQ

The values of $\Delta $H and $\Delta $S for the reaction,

C_(graphite) + CO₂(g) $ \to $  2CO_(g)

are 170 kJ and 170 J K^$-$1, respectively. This reaction will be spontaneous at

A

910 K

B

1110 K

C

510 K

D

710 K

Question 52: Palette 52/86

NEET 2009 MCQ

From the following bond energies :
H $-$ H bond energy   : 431.37 kJ mol^$-$1
C $=$ C bond energy   : 606.10 kJ mol^$-$1
C $-$ C bond energy   : 336.49 kJ mol^$-$1
C $-$ H bond energy   : 410.50 kJ mol^$-$1
Enthalpy for the reaction,

will be

A

$-$ 243.6 kJ mol^$-$1

B

$-$ 120.0 kJ mol^$-$1

C

553.0 kJ mol^$-$1

D

1523.6 kJ mol^$-$1

Question 53: Palette 53/86

NEET 2008 MCQ

For the gas phase reaction,

PCl_5(g)  $\rightleftharpoons$ PCl_3(g) + Cl_2(g)

which of the following conditions are correct ?

A

$\Delta $H < 0 and $\Delta $S < 0

B

$\Delta $H > 0 and $\Delta $S < 0

C

$\Delta $H = 0 and $\Delta $S < 0

D

$\Delta $H > 0 and $\Delta $S > 0

Question 54: Palette 54/86

NEET 2008 MCQ

Bond dissociation enthalpy of H₂, Cl₂ and HCl are 434, 242 and 431 kJ mol^$-$1 respectively. Enthalpy of formation of HCl is

A

$-$ 93 kJ mol^$-$1

B

245 kJ mol^$-$1

C

93 kJ mol^$-$1

D

$-$ 245 kJ mol^$-$1

Question 55: Palette 55/86

NEET 2008 MCQ

Which of the following are not state functions ?
(I) q + w     (II) q
(III) w        (IV) H $-$ TS

A

(I), (II) and (III)

B

(II) and (III)

C

(I) and (IV)

D

(II), (III) and (IV)

Question 56: Palette 56/86

NEET 2007 MCQ

Given that bond energies of H $-$ H and Cl $-$ Cl are 430 kJ mol^$-$1 and 240 kJ mol^$-$1 respectively and $\Delta $H_f for HCl is $-$ 90 kJ mol^$-$1, bond enthalpy of HCl is

A

380 kJ mol^$-$1

B

425 kJ mol^$-$1

C

245 kJ mol^$-$1

D

290 kJ mol^$-$1

Question 57: Palette 57/86

NEET 2007 MCQ

Consider the following reactions :
(i) H⁺_(aq) + OH^$-$_(aq) = H₂O_(l),  $\Delta $H = $-$ X₁ kJ mol^$-$1
(ii) H_2(g) + 1/2O_2(g) = H₂O_(l),   $\Delta $H = $-$ X₂ kJ mol^$-$1
(iii) CO_2(g) + H_2(g) = CO_(g) + H₂O_(l),  $\Delta $H = $-$ X₃ kJ mol^$-$1
(iv) C₂H_2(g) + 5/2O_2(g) = 2CO_2(g) + H₂O_(l),    $\Delta $H = +X₄ kJ mol^$-$1

Enthalpy of formation of H₂O_(l) is

A

+X₃ kJ mol^$-$1

B

$-$X₄ kJ mol^$-$1

C

+X₁ kJ mol^$-$1

D

$-$X₂ kJ mol^$-$1

Question 58: Palette 58/86

NEET 2006 MCQ

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

A

2CO_(g) + O_2(g) $ \to $  2CO_2(g)

B

H_2(g) + Br_2(g) $ \to $ 2HBr_(g)

C

C_(s) + 2H₂O_(g) $ \to $ 2H_2(g) + CO_2(g)

D

PCl_5(g) $ \to $ PCl_3(g) + Cl_2(g)

Question 59: Palette 59/86

NEET 2006 MCQ

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

A

$-$ 358.5 kJ mol^$-$1

B

$-$ 508.9 kJ mol^$-$1

C

$-$ 208.1 kJ mol^$-$1

D

$-$ 269.9 kJ mol^$-$1

Question 60: Palette 60/86

NEET 2006 MCQ

The enthalpy and entropy change for the reaction:
Br_2(l) + Cl_2(g) $ \to $ 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

A

300 K

B

285.7 K

C

273 K

D

450 K

Question 61: Palette 61/86

NEET 2006 MCQ

Identify the correct statement for change of Gibb's energy for a system ($\Delta $G_system) at constant temperature and pressure.

A

If $\Delta $G_system < 0, the process is not spontaneous.

B

If $\Delta $G_system > 0, the process is spontaneous.

C

If $\Delta $G_system = 0, the system has attained equilibrium.

D

If $\Delta $G_system = 0, the system is till moving in a particular direction.

Question 62: Palette 62/86

NEET 2005 MCQ

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

A

Exothermic and increasing disorder

B

Exothermic and decreasing disorder

C

Endothermic and increasing disorder

D

Endothermic and decreasing disorder

Question 63: Palette 63/86

NEET 2005 MCQ

A reaction occurs spontaneously if

A

T$\Delta $S < $\Delta $H and both $\Delta $H and $\Delta $S are +ve

B

T$\Delta $S > $\Delta $H and $\Delta $H is +ve and $\Delta $S are $-$ve

C

T$\Delta $S > $\Delta $H and both $\Delta $H and $\Delta $S are +ve

D

T$\Delta $S = $\Delta $H and both $\Delta $H and $\Delta $S are +ve

Question 64: Palette 64/86

NEET 2005 MCQ

The absolute enthalpy of neutralisation of the reaction :

Mg(O)_(s) + 2HCl_(aq) $ \to $ MgCl_2(aq) + H₂O_(l) will be

A

$-$57.33 kJ mol^$-$1

B

greater than $-$ 57.33 kJ mol^$-$1

C

less than $-$ 57.33 kJ mol^$-$1

D

57.33 kJ mol^$-$1

Question 65: Palette 65/86

NEET 2004 MCQ

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

A

$-$ 221.1 kJ mol^$-$1

B

$-$339.3 kJ mol^$-$1

C

$-$ 439.3 kJ mol^$-$1

D

$-$ 523.2 kJ mol^$-$1

Question 66: Palette 66/86

NEET 2004 MCQ

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)

A

$-$ 6 J

B

$-$ 608 J

C

+ 304 J

D

$-$ 304 J

Question 67: Palette 67/86

NEET 2004 MCQ

If the bond energies of H $-$ H, Br $-$ Br, and H $-$ Br are 433, 192 and 364 kJ mol^$-$1 respectively, the $\Delta $H^o for the reaction

H_2(g) + Br_2(g) $ \to $ 2HBr_(g) is

A

$-$ 261 kJ

B

+103 kJ

C

+261 kJ

D

$-$103 kJ

Question 68: Palette 68/86

NEET 2004 MCQ

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

A

$\Delta {S_{system}} + \Delta {S_{surroundings}} > 0$

B

$\Delta {S_{system}} - \Delta {S_{surroundings}} > 0$

C

$\Delta {S_{system}} > 0\,\,\,$only

D

$\Delta {S_{surroundings}} > 0$ only

Question 69: Palette 69/86

NEET 2003 MCQ

Formation of solution from two components can be considered as
(i) Pure solvent $ \to $ separated solvent molecules, $\Delta $H₁
(ii) Pure solute $ \to $ separated solute molecules, $\Delta $H₂
(iii) Separated solvent and solute molecules $ \to $ solution, $\Delta $H₃
Solution so formed will be ideal if

A

$\Delta $H_soln = $\Delta $H₁ + $\Delta $H₂ + $\Delta $H₃

B

$\Delta $H_soln = $\Delta $H₁ + $\Delta $H₂ $-$ $\Delta $H₃

C

$\Delta $H_soln = $\Delta $H₁ $-$ $\Delta $H₂ $-$ $\Delta $H₃

D

$\Delta $H_soln = $\Delta $H₃ $-$ $\Delta $H₁ $-$ $\Delta $H₂

Question 70: Palette 70/86

NEET 2003 MCQ

The molar heat capacity of water at constant pressure, C, is 75 J K^$-$1 mol^$-$1. When 1.0 kJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature of water is

A

1.2 K

B

2.4 K

C

4.8 K

D

6.6 K

Question 71: Palette 71/86

NEET 2003 MCQ

What is the entropy change (in J K^$-$1 mol^$-$1) when one mole of ice is converted into water at 0^oC? (The enthalpy change for the conversion of ice to liquid water is 6.0 kJ mol^$-$1 at 0^oC).

A

20.13

B

2.013

C

2.198

D

21.98

Question 72: Palette 72/86

NEET 2003 MCQ

For the reaction,
C₃H_8(g) + 5O_2(g) $ \to $ 3CO₂(g) + 4H₂O_(l)
at constant temperature, $\Delta $H $-$ $\Delta $E is

A

+ RT

B

$-$3RT

C

+ 3RT

D

$-$ RT

Question 73: Palette 73/86

NEET 2003 MCQ

The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm^$-$3, respectively. If the standard free energy difference $\left( {\Delta {G^o}} \right)$ is equal to 1895 J mol^$-$1, the pressure at which graphite will be transformed into diamond at 298 K is

A

11.14 $ \times $ 10⁸ Pa

B

11.14 $ \times $ 10⁷ Pa

C

11.14 $ \times $ 10⁶ Pa

D

11.14 $ \times $ 10⁵ Pa

Question 74: Palette 74/86

NEET 2003 MCQ

For which one of the following equations is $\Delta $H^o_react equal to $\Delta $H^o_f for the product ?

A

Xe_(g) + 2F_2(g) $ \to $ XeF_4(g)

B

2CO_(g) + O_2(g) $ \to $ 2CO_2(g)

C

N_2(g) + O_3(g) $ \to $ N₂O_3(g)

D

CH_4(g) + 2Cl_2(g) $ \to $ CH₂Cl_2(l) + 2HCl_(g)

Question 75: Palette 75/86

NEET 2002 MCQ

2 mole of ideal gas at 27^oC temperature is expanded reversibly from 2 lit. to 20 lit. Find entropy change. (R = 2 cal/mol K)

A

92.1

B

0

C

4

D

9.2

Question 76: Palette 76/86

NEET 2002 MCQ

Which reaction is not feasible?

A

2KI + Br₂ $ \to $ 2KBr + I₂

B

2KBr + I₂ $ \to $ 2KI + Br₂

C

2KBr + Cl₂ $ \to $ 2KCl + Br₂

D

2H₂O + 2F₂ $ \to $ 4HF + O₂

Question 77: Palette 77/86

NEET 2002 MCQ

Unit of entropy is

A

J K^$-$1 mol^$-$1

B

J mol^$-$1

C

J^$-$1 K^$-$1 mol^$-$1

D

J K mol^$-$1

Question 78: Palette 78/86

NEET 2002 MCQ

In a closed insulated container a liquid is stirred with a paddle to increase the temperature which of the following is true ?

A

$\Delta $E = W $ \ne $ 0, q = 0

B

$\Delta $E = w = q $ \ne $ 0

C

$\Delta $E = 0, W = q $ \ne $ 0

D

W = 0, $\Delta $E = q $ \ne $ 0.

Question 79: Palette 79/86

NEET 2002 MCQ

Heat of combustion $\Delta $H^o for C_(s), H_2(g) and CH_4(g) are $-$ 94, $-$ 68 and $-$213 kcal/mol, then $\Delta $H^o for C_(s) + 2H_2(g) $ \to $ CH_4(g) is

A

$-$17 kcal

B

$-$111 kcal

C

$-$170 kcal

D

$-$85 kcal

Question 80: Palette 80/86

NEET 2001 MCQ

Change in enthalpy for reaction,

2H₂O_2(l) $ \to $ 2H₂O_(l) + O_2(g)

if heat of formation of H₂O_2(l) and H₂O_(l) are $-$188 and - 286 kJ/mol respectively, is

A

$-$ 196 kJ/mol

B

+ 196 kJ/mol

C

+948 kJ/mol

D

$-$ 948 kJ/mol

Question 81: Palette 81/86

NEET 2001 MCQ

When 1 mol of 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 ?

A

q = w = 500 J, $\Delta $E = 0

B

q = $\Delta $E = 500 J, w = 0

C

q = w = 500 J, $\Delta $E = 0

D

$\Delta $E = 0, q = w = $-$ 500 J

Question 82: Palette 82/86

NEET 2001 MCQ

PbO₂  $ \to $ PbO; $\Delta $G₂₉₈ < 0
SnO₂ $ \to $ SnO;  $\Delta $G₂₉₈ > 0

Most probable oxidation state of Pb and Sn will be

A

Pb⁴⁺, Sn⁴⁺

B

Pb⁴⁺, Sn²⁺

C

Pb²⁺, Sn²⁺

D

Pb²⁺, Sn⁴⁺

Question 83: Palette 83/86

NEET 2001 MCQ

Enthalpy of CH₄ + ${1 \over 2}$ O₂ $ \to $ CH₃OH is negative. If enthalpy of combustion of CH₄ and CH₃OH are x and y respectively. Then which relation is correct?

A

x > y

B

x < y

C

x = y

D

x³ y

Question 84: Palette 84/86

NEET 2000 MCQ

The entropy change in the fusion of one mole of a solid melting at 27^oC (latent heat of fusion is 2930 J mol^–1) is :

A

9.77 J/mol-K

B

10.77 J/mol-K

C

9.07 J/mol-K

D

0.977 J/mol-K

Question 85: Palette 85/86

NEET 2000 MCQ

2Zn + O₂ $ \to $ 2ZnO;  $\Delta $G^o = $-$ 616 J
2Zn + S₂ $ \to $ 2ZnS;  $\Delta $G^o = $-$ 293 J
S₂ + 2O₂ $ \to $ 2SO₂;   $\Delta $G^o = $-$408 J
$\Delta $G^o for the following reaction
2ZnS + 3O₂ $ \to $  2ZnO + 2SO₂ is

A

$-$ 731 J

B

$-$ 1317 J

C

$-$ 501 J

D

+ 731 J

Question 86: Palette 86/86

NEET 2000 MCQ

For the reaction,
C₂H₅OH_(l) + 3O_2(g) $ \to $ 2CO_2(g) + 3H₂O_(l)
which one is true

A

$\Delta $H = $\Delta $E $-$RT

B

$\Delta $H = $\Delta $E + RT

C

$\Delta $H = $\Delta $E + 2RT

D

$\Delta $H = $\Delta $E $-$ 2RT