A gas can expand from 100 mL to 250 mL under a constant pres

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 Multiple Choice QuestionsMultiple Choice Questions

661.

Hfusion of a substance is 'x' and Hvap is 'y', then Hsublimation will be

  • x + y

  • x - y

  • x/y

  • y/x


662.

Assertion : Many endothermic reactions that are not spontaneous at room temperature become spontaneous at high temperature.

Reason : Entropy of the system increases with increase in temperature.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


663.

Ssurr for an exothermic reaction is

  • always positive

  • always negative

  • zero

  • may be positive or negative


664.

Assertion : As a salt such as NaCl dissolves, the Na+ and Cl- ions leaving the crystal lattice acquire far greater freedom.

Reason : In thermodyanamic terms, the formation of solution occurs with a favourable change in free energy, i.e., H has a high positive value and TS a low negative value.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


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665.

In exothermic reaction heat is :

  • given out

  • absorbed

  • not involved

  • given out or absorbed


666.

For a spontaneous process the correct statement is

  • entropy of the system always increases.

  • free energy of the system always increases.

  • total entropy change is always negative.

  • total entropy change is always positive.


667.

Distribution law was given by :

  • Henry

  • Vant Hoff

  • Nernst

  • Ostwald


668.

The enthaply change (H) for the reaction

       N2(g) + 3H2(g) 2NH3(g)

is -92.38 kJ at 298K . The internal energy change U at 298K is

  • -92.38 kJ

  • -87.42 kJ

  • -97.34 kJ

  • -89.9 kJ


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669.

A gas can expand from 100 mL to 250 mL under a constant pressure of 2 atm .The work done by gas is :

  • 30.38 joule

  • 25 joule

  • 5 k joule

  • 16 joule


A.

30.38 joule

V1 = 100 mL

V2 = 250 mL

Pressure P = 2 atm or 2 x 1.01 x 105 Nm-2

Work done by the' gas

W = PV or P (V2 - V1)

Put the value in given formula

W = 2 X 1.01 x 105 (0.250 x 10-3 -0.100 x 10-3)

= 2 x 1.01 x 105 x .15 x 10-3

= 30.38 joule


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670.

Hf° (298 K) of methanol is given by the chemical equation

  • CH4 (g)12O2 (g) →CH3OH(g)

  • C (graphite) + 12O2 (g) + 2H2 → CH3OH(l)

  • C (diamond) + 12O2(g) + 2H2(g) → CH3OH(l)

  • CO(g) + 2H2 → CH3OH(l)


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