Minimum work is obtained when 1 kg of...gas expanded under 500 kP

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 Multiple Choice QuestionsMultiple Choice Questions

421.

Which of the following is not a state function?

  • Internal energy

  • Enthalpy

  • Work

  • Entropy


422.

Enthalpy (H) is equal to

  • internal energy (E)

  • product of pressure (p) and volume (V) of gas

  • internal energy (E)+ pV

  • work (W) done by a system


423.

In an isothermal process

  • q = 0 and E = 0

  • q ≠ 0 and E = 0

  • q = 0 and E ≠ 0

  • q ≠ 0 and E ≠ 0


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424.

Minimum work is obtained when 1 kg of...gas expanded under 500 kPa to 200 kPa pressure at 0°C

  • chlorine

  • oxygen

  • nitrogen

  • methane


A.

chlorine

Work obtained in isothermal,

W = -2.303 nRT log p1p2

Given, p1 = 500 kPa; p2 = 200 kPa
 W = -2.303 nRT log 500200

        = -2.303 nRT × 0.3980 nRT

 Minimum work will be obtained when number of moles (n) is minimum.

Moles of substances, mass = 1kg = 1000 gm

(i) Moles of Cl2 = 1000/ 71

(ii) Moles of O2 = 1000/ 32

(iii) Moles of N2 = 1000/ 28

(iv) Moles of CH4 = 1000/ 16

Since, moles of Cl2 are least. Therefore, minimum work is obtained when 1 kg of chlorine gas expands.


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425.

Which one of the following represents the graph between log p (on Y-axis) and 1/T  on X-axis)? (p = vapour pressure of a liquid, T = absolute temperature).


426.

When 10 g of methane is completely burnt in oxygen, the heat evolved is 560 kJ. What is the heat of combustion (in kJ mol-1) of methane?

  • -1120

  • -968

  • -896

  • -560


427.

Calculate the heat of combustion (in kJ) of methane from the following data :

(i) C(graphite) + 2H2 (g) → CH(g) ; H = -74.8 kJ

(ii) C(graphite) + O2 (g) → CO2 (g) ; H = -393.5 kJ

(iii) H2 (g) + 1/2 O2 (g) → H2O (l) ; H = -286.2 kJ

  • -891.1

  • -816.3

  • -965.9

  • -1040.7


428.

Which of the following is an endothermic reaction?

  • N2 (g) + 3H2 (g) - 92 kJ → 2NH3 (g)

  • N2 (g) + O2 (g) + 180.8 kJ → 2NO (g)

  • H2 (g) + Cl2 (g) → 2HCl (g) + 184.6 kJ

  • C (graphite) + 2H2 (g) → CH2 (g) + 74.8 kJ


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429.

Which of the following is not correct?

  • 3O2 dischargesilent electric 2O3H = -284.5 kJ

  • Ozone undergoes addition reaction with unsaturated carbon compounds

  • Sodium thuosulphate reacts with I2 to form sodium tetrathionate and sodium iodide.

  • Ozone oxidises lead sulphide to lead sulphate.


430.

Which of the following is not correct?

  • Dissolution of NH4Cl in excess of water is an endothermic process.

  • Neutralisation process is always exothermic

  • The absolute value of enthalpy (H) can be determined experimentally.

  • The heat of reaction at constant volume is denoted by ΔE.


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