# Thermochemistry and Thermodynamics Test 1

Total Questions:50 Total Time: 75 Min

Remaining:

## Questions 1 of 50

Question:The total internal energy change for a reversible isothermal cycles is

Always 100 calories per degree

Always negative

0

Always positive

## Questions 2 of 50

Question:A well stoppered thermos flask contains some ice cubes. This is an example of a

Closed system

Open system

Isolated system

Non-thermodynamic system

## Questions 3 of 50

Question:Identify the intensive quantity from the following

Enthalpy and temperature

Volume and temperature

Enthalpy and volume

Temperature and refractive index

## Questions 4 of 50

Question:Internal energy is an example of

Path function

State function

Both 1 and 2

None of these

## Questions 5 of 50

Question:The process, in which no heat enters or leaves the system, is termed as

Isochoric

Isobaric

Isothermal

## Questions 6 of 50

Question:The intensive property among these quantities is

Enthalpy

Mass/volume

Mass

Volume

## Questions 7 of 50

Question:The law of Lavoisier and Laplace illustrates

The principle of conservation of energy

Equivalence of mechanical and thermal energy

The principle of conservation of matter

Equivalence of mechanical and chemical energy

## Questions 8 of 50

Question:For the reaction $${N_2} + 3{H_2}$$$$\leftrightarrow$$$$2N{H_3};\,\Delta H =$$

$$\Delta E - RT$$

$$\Delta E - 2RT$$

$$\Delta E + RT$$

$$\Delta E + 2RT$$

## Questions 9 of 50

Question:If $$\Delta H$$ is the change in enthalpy and $$\Delta E$$ the change in internal energy accompanying a gaseous reaction

$$\Delta H$$ is always greater than $$\Delta E$$

$$\Delta H < \Delta E$$ only if the number of moles of the products is greater than the number of the reactants

$$\Delta H$$ is always less than $$\Delta E$$

$$\Delta H < \Delta E$$ only if the number of moles of the products is less than the number of moles of the reactants

## Questions 10 of 50

Question:Hess law of heat summation includes

Initial reactants only

Initial reactants and final products

Final products only

Intermediates only

## Questions 11 of 50

Question:An ideal gas at constant temperature and pressure expands, then its

Internal energy remains same

Internal energy decreases

Internal energy increases

Entropy first increases and then decreases

## Questions 12 of 50

Question:The internal energy of a substance

Increases with increase in temperature

Decreases with increase in temperature

Can be calculated by the relation $$E = m{c^2}$$

Remains unaffected with change in temperature

## Questions 13 of 50

Question:One mole of an ideal gas is allowed to expand freely and adiabatically into vacuum until its volume has doubled. A statement which is not true concerning this expression is

$$\Delta H = 0$$

$$\Delta S = 0$$

$$\Delta E = 0$$

$$W = 0$$

## Questions 14 of 50

Question:At $${27^o}C,$$ one mole of an ideal gas is compressed isothermally and reversibly from a pressure of 2 atm to 10 atm. The values of $$\Delta E$$ and q are $$(R = 2)$$

0, – 965.84 cal

965.84 cal, + 965.84 cal

+ 865.58 cal, – 865.58 cal

865.58 cal, – 865.58 cal

## Questions 15 of 50

Question:The work done during the expansion of a gas from a volume of $$4d{m^3}$$ to $$6d{m^3}$$ against a constant external pressure of $$3atm$$ is ($$1L\,atm\, = 101.32\,J$$)

+ 304 J

304 J

6 J

608 J

## Questions 16 of 50

Question:For the reaction, $${A_{(s)}} + 2{B_{(g)}} \to 4{C_{(s)}} + {D_{(l)}}$$. $$\Delta H$$ and $$\Delta U$$ are related as...........

$$\Delta H = \Delta U$$

$$\Delta H = \Delta U + 3RT$$

$$\Delta H = \Delta U + RT$$

$$\Delta H = \Delta U - 3RT$$

## Questions 17 of 50

Question:The $$\Delta S$$ for the vaporisation of 1 mol of water is 88.3 J/mole K. The value of $$\Delta S$$ 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

$$\frac{1}{{88.3}}$$ J/mol K

## Questions 18 of 50

Question:For which reaction from the following, $$\Delta S$$ will be maximum

$$Ca(s) + \frac{1}{2}{O_2}(g) \to CaO(s)$$

$$CaC{O_3}(s) \to CaO(s) + C{O_2}(g)$$

$$C(s) + {O_2}(g) \to C{O_2}(g)$$

$${N_2}(g) + {O_2}(g) \to 2NO(g)$$

## Questions 19 of 50

Question:For which of the processes is $$\Delta S$$ negative

$${H_2}(g) \to 2H(g)$$

$${N_2}(g)\,1atm \to {N_2}(g)\,8\,atm$$

$$2S{O_3}(g) \to 2S{O_2}(g) + {O_2}(g)$$

$${C_{(diamond)}} \to {C_{(graphite)}}$$

## Questions 20 of 50

Question:Identify the correct statement regarding entropy

At $${0^o}C$$, , the entropy of a perfectly crystalline substance is taken to be zero

At absolute zero of temperature, the entropy of a perfectly crystalline substance is $$+ ve$$

At absolute zero of temperature, the enthalpy of all crystalline substances is taken to be one.

At absolute zero of temperature, the entropy of all crystalline substances is taken to be zero

## Questions 21 of 50

Question:The entropy change, in the conversion of one mole of liquid water at 373 K to vapour at the same temperature is (Latent heat of vaporization of water, $$\Delta {H_{vap}} = 2.257\,kJ/g)$$

105.9$$J{k^{ - 1}}$$

$$107.9\,\,J{k^{ - 1}}$$

$$108.9\,\,J{k^{ - 1}}$$

$$109.9\,\,J{k^{ - 1}}$$

## Questions 22 of 50

Question:A heat engine absorbs heat $${Q_1}$$ at temperature $${T_1}$$ and heat $${Q_2}$$ at temperature $${T_2}$$. Work done by the engine is $$({Q_1} + {Q_2})$$. This data

Violates Ist law of thermodynamics

Violates Ist law of thermodynamics if $${Q_1}$$ is –ve

Violates Ist law of thermodynamics if $${Q_2}$$ is –ve

Does not violate Ist law of thermodynamics

## Questions 23 of 50

Question:The standard entropies of $$C{O_2}(g),\,C(s)$$ and $${O_2}(g)$$ are 213.5, 5.740 and 205 $$J{K^{ - 1}}$$ respectively. The standard entropy of formation of $$C{O_2}$$ is

$$2.76\,J{K^{ - 1}}$$

$$2.12\,J{K^{ - 1}}$$

$$1.12\,J{K^{ - 1}}$$

$$1.40\,J{K^{ - 1}}$$

## Questions 24 of 50

Question:Which law of thermodyanamics help in calculating entropy at different temperatures

First law

Second law

Third law

Zeroth law

## Questions 25 of 50

Question:The following is (are) endothermic reaction

Combustion of methane

Decomposition of water

Dehydrogenation of ethane to ethylene

Conversion of graphite to diamond

2,3 and 4 are correct

## Questions 26 of 50

Question:Evaporation of water is

An endothermic change

An exothermic change

A process where no heat change occurs

A process accompanied by chemical reaction

## Questions 27 of 50

Question:The mutual heat of neutralisation of 40 gm of $$NaOH$$ and 60 gm $$C{H_3}COOH$$ will be

56.1 kcal

Less than 56.1 kcal

More than 56.1 kcal

13.7 kcal

## Questions 28 of 50

Question:The heat of formations of $$CO(g)$$ and $$C{O_2}(g)$$ are $$- 26.4$$ kcal and $$- 94.0$$ kcal respectively. The heat of combustion of carbon monoxide will be

$$+ 26.4\,kcal$$

$$- 67.6\,kcal$$

$$- 120.6\,kcal$$

$$+ 52.8\,kcal$$

## Questions 29 of 50

Question:The heat of formation of $${H_2}O(l)$$ is – 68.0 kcal, the heat of formation of $${H_2}O(g)$$ is likely to be

68.0 kcal

67.4 kcal

80.0 kcal

58.3 kcal

## Questions 30 of 50

Question:Which of the following fuels will have the highest calorific value (kJ/kg)

Charcoal

Kerosene

Wood

Dung

## Questions 31 of 50

Question:A reaction that takes place with the absorption of energy is

Burning of a candle

Rusting of iron

Electrolysis of water

Digestion of food

## Questions 32 of 50

Question:Which of the following is an endothermic reaction

$$2{H_2} + {O_2} \to 2{H_2}O$$

$${N_2} + {O_2} \to 2NO$$

$$2NaOH + {H_2}S{O_4} \to N{a_2}S{O_4} + 2{H_2}O$$

$$3{O_2} + {C_2}{H_5}OH \to 2C{O_2} + 3{H_2}O$$

## Questions 33 of 50

Question:In which of the following reactions does the heat change represent the heat of formation of water

$$2{H_2}(g) + {O_2}(g) \to 2{H_2}O(l);\,\Delta H = - 116\,kcal$$

$${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(l);\,\Delta H = - 58\,kcal$$

$${H^ + }(aq.) + O{H^ - }(aq.) \to 2{H_2}O(l);\,\Delta H = - 13.7\,kcal$$

$${C_2}{H_2}(g) + 2\frac{1}{2}{O_2}(g) \to 2C{O_2}(g) + {H_2}O(l)$$; $$\Delta H = - 310\,kcal$$

## Questions 34 of 50

Question:Values of heats of formation for $$Si{O_2}$$and $$MgO$$ are $$- 48.4$$ and $$- 34.7\,kJ$$ respectively. The heat of the reaction $$2Mg + Si{O_2} \to 2MgO + Si$$ is

$$21.16\,kJ$$

$$- 21.10\,kJ$$

$$- 13.62\,kJ$$

$$13.6\,kJ$$

## Questions 35 of 50

Question:Enthalpy of formation of $$HF$$ and $$HCl$$ are $$- \,161\,kJ$$ and $$- \,92\,kJ$$ respectively. Which of the following statements is incorrect

$$HCl$$ is more stable than $$HF$$

$$HF$$ and $$HCl$$ are exothermic compounds

The affinity of fluorine to hydrogen is greater than the affinity of chlorine to

$$HF$$ is more stable than $$HCl$$

## Questions 36 of 50

Question:The heat of reaction at constant pressure is given by

$${E_P} - {E_R}$$

$${E_R} - {E_P}$$

$${H_P} - {H_R}$$

$${H_R} - {H_P}$$

## Questions 37 of 50

Question:The combustion enthalpies of carbon, hydrogen and methane are $$- 395.5\,kJ\,mo{l^{ - 1}}$$, $$- 285.8\,kJ\,mo{l^{ - 1}}$$ and $$- 890.4\,kJ\,mo{l^{ - 1}}$$ respectively at $${25^o}C$$. The value of standard formation enthalpies of methane at that temperature is

$$890.4\,kJ\,mo{l^{ - 1}}$$

$$- 298.8\,kJ\,mo{l^{ - 1}}$$

$$- 74.7\,kJ\,mo{l^{ - 1}}$$

$$- 107.7\,kJ\,mo{l^{ - 1}}$$

## Questions 38 of 50

Question:Equal volumes of methanoic acid and sodium hydroxide are mixed. If $$x$$ is the heat of formation of water, then heat evolved on neutralisation is

More than $$x$$

Equal to $$x$$

Twice of $$x$$

Less than $$x$$

## Questions 39 of 50

Question:The heat change for the following reaction at $${298^o}K$$ and at constant pressure is $$+ 7.3\,kcal$$ , $${A_2}B(s)\, \to \,2A(s) + 1/2\,{B_2}(g)$$, $$\Delta H = + 7.3\,kcal$$. The heat change at constant volume would be

7.3 kcal

More than 7.3

Zero

None of these

## Questions 40 of 50

Question:The heat evolved in the combustion of benzene is given by the equation $${C_6}{H_6}(l) + 7\frac{1}{2}{O_2}(g)\,\, \to \,\,3{H_2}O(l) + 6C{O_2}(g)$$, $$\Delta H = 781.0\,kcal\,\,mo{l^{ - 1}}$$. Which of the following quantities of heat energy will be evolved when 39 g of benzene is burnt in an open container

122.25 kcal $$mo{l^{ - 1}}$$

390.5 kcal $$mo{l^{ - 1}}$$

1562.0 kcal $$mo{l^{ - 1}}$$

586.75 kcal $$mo{l^{ - 1}}$$

## Questions 41 of 50

Question:What is $$\Delta n$$ for combustion of 1 mole of benzene, when both the reactants and the products are gas at 298 K

0

3/2

3/2

1/2

## Questions 42 of 50

Question:If $$C + {O_2} \to C{O_2} + 94.2\,kcal$$, $${H_2} + \frac{1}{2}{O_2} \to \,{H_2}O + 68.3\,kcal$$, $$C{H_4} + 2{O_2}\, \to \,C{O_2} + 2{H_2}O + 210.8\,kcal$$. Then the possible heat of methane will be

47.3 kcal

20.0 kcal

45.9 kcal

47.3 kcal

## Questions 43 of 50

Question:1 mole of conc. HCl requires X moles of dilute NaOH for neutralisation and 1 mole of concentrate $${H_2}S{O_4}$$ requires Y moles of small dilute $$NaOH$$ then which of the following reaction is true

$$Y = \frac{1}{2}X$$

$$X = \frac{1}{2}Y$$

$$X = 2Y$$

None of these

## Questions 44 of 50

Question:Which of the reaction defines $$\Delta H_f^o$$

$${C_{({\rm{diamond}})}} + {O_2}(g)\, \to \,C{O_2}(g)$$

$$\frac{1}{2}{H_2}(g) + \frac{1}{2}{F_2}(g)\, \to \,HF(g)$$

$${N_2}(g) + 3{H_2}(g)\, \to \,2N{H_3}(g)$$

$$CO(g) + \frac{1}{2}{O_2}(g)\, \to \,C{O_2}(g)$$

## Questions 45 of 50

Question:Given : $$2Fe + \frac{3}{2}{O_2} \to F{e_2}{O_3},\,\Delta H = - 193.4\,kJ$$; , $$Mg + \frac{1}{2}{O_2} \to MgO,\,\Delta H = - 140.2\,kJ$$. What is the $$\Delta H$$ of the reaction $$Mg + F{e_2}{O_3} \to 3MgO + 2Fe$$

1802 kJ

+1802 kJ

800 kJ

+ 228 kJ

## Questions 46 of 50

Question:The enthalpy change $$(\Delta H)$$ for the neutralisation of $$1M\,HCl$$ by caustic potash in dilute solution at $$298K$$ is

68 kJ

65 kJ

57.3 kJ

50 kJ

## Questions 47 of 50

Question:At 300 K, the reactions which have following values of thermodynamic parameters occur spontaneously

$$\Delta {G^o} = - 400\,\,kJ\,\,mo{l^{ - 1}}$$

$$\Delta {H^o} = 200\,\,kJ\,\,mo{l^{ - 1}},\,\,\,\Delta {S^o} = - 4\,\,J{K^{ - 1}}mo{l^{ - 1}}$$

$$\Delta {H^o} = - 200\,kJ\,mo{l^{ - 1}},\,\,\Delta {S^o} = 4\,J{K^{ - 1}}mo{l^{ - 1}}$$

$$\Delta {H^o} = 200\,J\,mo{l^{ - 1}},\,\,\Delta {S^o} = 40\,J{K^{ - 1}}mo{l^{ - 1}}$$

1,3 and 4 are correct

## Questions 48 of 50

Question:The relation $$\Delta G = \Delta H - T\Delta S$$ was given by

Boltzmann

Gibbs–Helmholtz

Thomson

## Questions 49 of 50

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

$$9.92 \times {10^5}Pa$$

$$9.92 \times {10^8}Pa$$

$$9.92 \times {10^7}Pa$$

$$9.92 \times {10^6}Pa$$

## Questions 50 of 50

Question:The free energy change for the following reactions are given below, $${C_2}{H_2}(g) + \frac{5}{2}{O_2}(g)\, \to$$$$2C{O_2}(g) + {H_2}O(l);\,\Delta {G^o} = - 1234\,kJ$$ $$C(s) + {O_2}(g)\, \to C{O_2}(g)\,\,\Delta {G^o} = - 394\,kJ$$, $${H_2}(g) + \frac{1}{2}{O_2}(g)\, \to \,{H_2}O(l)\,\,\,\Delta {G^o} = - 237kJ$$What is the standard free energy change for the reaction $${H_2}(g) + 2\,C\,(s) \to {C_2}{H_2}(g)$$