Enthalpy is equal to : from Chemistry JEE Year 2007 Free Solved

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

When a solid melts reversibly :

  • H decreases

  • G increases

  • E decreases

  • S increases


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2.

Enthalpy is equal to :

  • T2(G/T)TP

  • -T2(G/T)TP

  • T2(G/T)TV

  • -T2(G/T)TV


B.

-T2(G/T)TP

The Gibbs-Helmholtz equation is as :   G= H + T GTPDividing above equation by T2GT2= HT2+ 1TGTThis on rearrangement becomes (G/T)TP=HT2H= -T2(G/T)TPWhere H= enthalpy


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3.

Condition for spontaneity in an isothermal process is

  • A + W < 0

  • G + U <0

  • A + U>0

  • G -U<0


4.

2C(s) + 2O2(g)  2CO2(g);              H= -787 kJ ....(i)H2(g) + 12O2(g)  H2O (l);              H = -286 kJ ...(ii)C2H2(g) + 212O2(g)  2CO2(g) + H2O (l) ;  H= -1310 kJ ...(iii)

The heat of formation of acetylene is :

  • -1802 kJ

  • +1802 kJ

  • +237 kJ

  • -800 kJ


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5.

Given the equilibrium system:

NH4Cl(s)  NH4+(aq) + Cl-(aq)       (H =+3.5 kcal/mol).

What change will shift the equilibrium to the right?

  • Decreasing the temperature

  • Increasing the temperature

  • Dissolving NaCl crystals in the equilibrium mixture

  • Dissolving NH4NO3 crystals in the equilibrium mixture


6.

Equivalent amounts of H2 and I2, are heated in a closed vessel till equilibrium is obtained. If 80% of the hydrogen can be converted to HI, the Kc at this temperature is :

  • 64

  • 16

  • 0.25

  • 4


7.

For the reaction H2(g) + I2(g)  2HI(g), the equilibrium constant KP changes with: 

  • total pressure

  • catalyst

  • the amount H2 and I2

  • temperature


8.

In TeClthe central atom tellurium involves :

  • sp3 hybridisation 

  • sp3d hybridisation 

  • sp3d2 hybridisation 

  • dsp2 hybridisation 


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9.

A nuclear reaction of U92235 with a neutron produces Kr3690 and two neutrons. Other element produced in this reaction is

  • Te52137

  • Cs55144

  • Ba56137

  • Ba56144


10.

A coordiante bond is a dative covalent bond. Which of the below is true?

  • Three atom form bond by sharing their electrons

  • Two atom form bond by sharing their electrons

  • Two atoms form bond and one of them provides both electrons

  • Two atoms form bond by sharing electrons obtained from third atom


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