Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

 Multiple Choice QuestionsMultiple Choice Questions

11.

(∆H −∆U) for the formation of carbon monoxide (CO) from its elements at 298 K is
(R = 8.314 J K–1 mol–1)

  • –1238.78 J mol–1

  • 1238.78 J mol–1

  • –2477.57 J mol–1

  • –2477.57 J mol–1


A.

–1238.78 J mol–1

∆H −∆U =∆ngRT
= (-1 x 8.314 x 298)/2
= - 1238.78

229 Views

12.

Identify the correct statement regarding a spontaneous process –

  • For a spontaneous process in an isolated system, the change in entropy is positive

  • Endothermic processes are never spontaneous

  • Exothermic processes are always spontaneous

  • Exothermic processes are always spontaneous


A.

For a spontaneous process in an isolated system, the change in entropy is positive

197 Views

13.

The work of 146 kJ is performed in order to compress one kilo mole of gas adiabatically and in this process the temperature of the gas increases by 7° C. The gas is

(R = 8.3 J mol−1 K−1 )

  • monoatomic

  • diatomic

  • triatomic

  • triatomic


B.

diatomic

146 = Cv∆T
⇒ Cv = 21 J/mol K

566 Views

14.

A Carnot engine, having an efficiency of η = 1/10 as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is

  • 99 J

  • 90 J

  • 1 J

  • 1 J


B.

90 J

straight W space equals space straight Q subscript 1 space open parentheses straight T subscript 1 over straight T subscript 2 minus 1 close parentheses space space space space straight eta space equals space 1 minus straight T subscript 2 over straight T subscript 1
10 space equals space straight Q subscript 2 space open parentheses 10 over 9 minus 1 close parentheses space space space space 1 over 10 space equals space 1 minus straight T subscript 2 over straight T subscript 1
rightwards double arrow space space straight T subscript 2 over straight T subscript 1 space equals 1 space minus 1 over 10 space equals space 9 over 10
10 space equals space straight Q subscript 2 space open parentheses 1 over 9 close parentheses
rightwards double arrow space straight T subscript 1 over straight T subscript 2 space equals space 10 over 9
straight Q subscript 2 space equals space 90 space straight J
590 Views

15.

In the conversion of limestone to lime, CaCO3(s) → CaO(s) + CO2(g) the values of ∆Hº and ∆Sº are + 179.1 kJ mol–1 and 160.2 J/K respectively at 298K and 1 bar. Assuming that ∆Hº and ∆Sº do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is

  • 1008 K

  • 1200 K

  • 845 K

  • 845 K


D.

845 K

We know, ∆G = ∆H-T∆S
So, lets find the equilibrium temperature, i.e. at which
∆G = 0
∆H-T∆S
T= 179.1 x 1000/160.2
= 1118 K
So, at the temperature above this, the reaction becomes will spontaneous.

180 Views

16.

The standard molar heat of formation of ethane, CO2 and water (l) are -21.1, -94.1 and -68.3 kcal respectively. The standard molar heat of combustion of ethane will be

  • -372 kcal

  • 162 kcal

  • -240 kcal

  • 183.5 kcal


A.

-372 kcal

Hreaction = Σ H of product  - Σ H of reactants HfC2H6 = -21.1 kcal,HfCO2= -94.1 kcal,HfH2O= -68.3 kcal<C2H6+ 72O2  2CO2 + 3H2OHcombution =[ 2HfCO2+ 3HfH2O]-[HfC2H6+72HfO]= [2 ×(-94.1) + 3(-68.3)] - [-21.1+ 72×(0)]= (-188.2- 204.9) + 21.1 = -393.1 + 21.1 = -372 kcal


17.

In the reaction,
2Al(s) + 6HCl(aq) → 2Al3+ (aq) + 6Cl¯(aq) + 3H2(g)

  • 6L HCl(aq) is consumed for every 3L H2(g) produced

  • 33.6 L H2(g) is produced regardless of temperature and pressure for every mole Al that reacts

  • 67.2 L H2(g) at STP is produced for every mole Al that reacts

  • 67.2 L H2(g) at STP is produced for every mole Al that reacts


D.

67.2 L H2(g) at STP is produced for every mole Al that reacts

2Al(s) + 6HCl(aq) → 2Al3+ (aq) + 6Cl¯(aq) + 3H2(g)

For each mole of HCl reacted, 0.5 mole of H2 gas is formed at STP.
1 mole of an ideal gas occupies 22.4 lit at STP.
Volume of H2 gas formed at STP per mole of HCl reacted is 22.4 × 0.5 litre

213 Views

18.

The enthalpy changes for the following processes are listed below:
Cl2(g) = 2Cl(g), 242.3 kJ mol–1
I2(g) = 2I(g), 151.0 kJ mol–1
ICl(g) = I(g) + Cl(g), 211.3 kJ mol–1
I2(s) = I2(g), 62.76 kJ mol–1
Given that the standard states for iodine and chlorine are I2(s) and Cl2(g), the standard enthalpy of formation for ICl(g) is

  • –14.6 kJ mol–1

  • –16.8 kJ mol–1

  • +16.8 kJ mol–1

  • +16.8 kJ mol–1


C.

+16.8 kJ mol–1

1 half straight I subscript 2 space left parenthesis straight s right parenthesis space space plus 1 half space Cl subscript 2 space rightwards arrow with space on top space ICl space left parenthesis straight g right parenthesis
increment straight H space equals space open square brackets 1 half increment straight H subscript straight I subscript 2 left parenthesis straight s right parenthesis space rightwards arrow straight I subscript 2 left parenthesis straight g right parenthesis end subscript space plus space 1 half straight mu subscript straight I minus straight I end subscript space plus 1 half straight mu subscript Cl minus Cl end subscript close square brackets space minus space left square bracket straight mu subscript straight I minus Cl end subscript right square bracket
space space equals open parentheses 1 half space straight x space 62.76 space space plus 1 half space straight x space 151.0 space plus 1 half space straight x space 242.3 close parentheses space minus left parenthesis 211.3 right parenthesis
space equals space 228.03 space minus 211.3
increment straight H space equals space 16.73
511 Views

19.

When a system is taken from state i to state f along the path iaf, it is found that Q = 50 cal and W = 20 cal. Along the path’ ibf Q = 36 cal. W along the path ibf is

  • 6 cal

  • 66 cal

  • 16 cal

  • 16 cal


A.

6 cal

259 Views

20.

When a solid melts reversibly :

  • H decreases

  • G increases

  • E decreases

  • S increases


D.

S increases

When a solid melts, its entropy (S) increases because on changes from solid to liquid disorder or randomness of molecules increases.