For the reaction X2O4 (l) -->  2XO2 (g) ΔU = 2.1 kcal, Δ

Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

What is the maximum number of orbitals that can be identified with the following quantum numbers?

n=3, l =1, m1 = 0

  • 1

  • 2

  • 3

  • 3

4451 Views

2.

Calculate the energy in joule corresponding to light of wavelength 45mm: (Planck's constant h=6.63 x10-34)Js; speed of light c= 3 x 108 ms-1)

  • 6.67 x 1015

  • 6.67 x 1011

  • 4.42 x 10-15

  • 4.42 x 10-15

1495 Views

3.

Equal masses of H2, O2 and methane have been taken in a container of volume V at temperature 270 C in identical conditions. The ratio of the volumes of gases H2 : O2: CH4 would be 

  • 8:16:1

  • 16:8:1

  • 16:1:2

  • 16:1:2

2981 Views

4.

Which of the following salts will give highest pH in water?

  • KCl

  • NaCl

  • Na2CO3

  • Na2CO3

1725 Views

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5.

When 22.4 L of H2 (g) is mixed with 11.2 L of Cl2 (g), each of at STP, the moles of HCl (g) formed is equal to

  • 1 mole of HCl (g)

  • 2 moles of HCl (g)

  • 0.5 mole of (g) 

  • 0.5 mole of (g) 

3178 Views

6.

Which of the following statement is correct for the spontaneous absorption of a gas?

  • ΔS is negative and therefore, ΔH should be highly positive
  • ΔS is negative and therefore, ΔH should be highly negative
  • ΔS is positive and therefore, ΔH should be negative
  • ΔS is positive and therefore, ΔH should be negative
1139 Views

7.

For the reversible reaction,

straight N subscript 12 space left parenthesis straight g right parenthesis space plus 3 straight H subscript 2 left parenthesis straight g right parenthesis space rightwards harpoon over leftwards harpoon 2 NH subscript 3 space left parenthesis straight g right parenthesis space plus Heat
the equilibrium shifts in the forward direction

  • by increasing the concentration of NH3 (g)

  • by decreasing the pressure

  • by decreasing the concentrations of N2 (g)  and H2(g)

  • by decreasing the concentrations of N2 (g)  and H2(g)

1432 Views

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8.

For the reaction X2O4 (l) -->  2XO2 (g) ΔU = 2.1 kcal, ΔS = 20 cal K-1 at 300 K hence ΔG is

  • 2.7 kcal

  • -2.7kcal

  • 9.3 kcal 

  • 9.3 kcal 


B.

-2.7kcal

The change in Gibbs free energy is given by

ΔG = ΔH-TΔS

Where, ΔH = enthalpy of the reaction

ΔS = entropy of reaction
Thus, in order to determine ΔG, the values of ΔH must be known. The value of ΔH can be calculated by the equation
ΔH = ΔU + ΔngRT
Where (ΔU) = change in internal energy

Δng = (number of moles of gaseous products)-(number of moles of gaseous reactant) = 2-0 =2
R = gas constant = 2 cal
But, ΔH= Δu +  ΔngRT 
Δu  =2.1 kcal = 2.1 x 103 cal

[1kcal = 103 cal]
therefore,
ΔH = (2.1 x 103) +(2x2x300) =3300 cal
Hence, ΔG = ΔH-TΔS
 ΔG = (3300)-(300 x20)
 ΔG =-2700 cal
 ΔG =-2.7 Kcal

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9.

For a given exothermic reaction Kp and Kp' are the equilibrium constant at temperatures T1 and T2 respectively. Assuming that heat of reaction si constant in temperature range between T1 and T2 it is readily observed that

  • Kp> Kp'

  • Kp< Kp'

  • Kp = Kp'

  • Kp = Kp'

1365 Views

10.

which of the following orders of ionic radii is correctly represented?

  • H- > H >H+

  • Na+ >F- >O2-

  • F- > O2->Na+

  • F- > O2->Na+

1051 Views

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