The work done during combustion of 9 × 10-2 kg of ethane, C

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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1.

The work done during combustion of 9 × 10-2 kg of ethane, C2H6 (g) at 300 K is (Given R = 8.314 J deg-1 mol-1, atomic mass C = 12, H= 1).

  • 6.236 kJ

  • -6.236 kJ

  • 18.71 kJ

  • -18.71 kJ


C.

18.71 kJ

Work done in a chemical reaction, 

W = ngRT

where, ng = number of moles of gaseous products - number of moles of gaseous reactants.

Combustion of ethane is-

C2H6 (g) + 72O2 (g) → 2CO2 (g) + 3H2O (l)

ng = 2 - 4.5 = -2.5

W = (2.5 mol) (8.314 JK-1 mol-1) × 300 K

    = 6235.5 kJ = 6.2355 J

Now, 1 mole of C2H6 = 30 gm of C2H6 = 6.2355 kJ

Work done for combustion of 30 gm of C2H= 6.2355 kJ

 Work done for combustion of 90 gm of C2H

6.2355 × 9030 

= 18.7065 kJ = 18.71 kJ


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2.

The molality of solution containing 15.20 g of urea, (molar mass = 60) dissolved in 150 g of water is

  • 1.689 mol kg-1

  • 0.1689 mol kg-1

  • 0.5922 mo kg-1

  • 0.2533 mol kg-1


3.

Identify the weakest oxidising agent among the following.

  • Li+

  • Na+

  • Cd+

  • I2


4.

Calculate the work done during compression of 2 mol of an ideal gas from a volume of 1 m3 to 10 dm3 300K against a pressure of 100 KPa

  • -99 kJ

  • +99 kJ

  • +22.98 kJ

  • -22.98 kJ


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5.

Which element among the following does form pπ - pπ multiple bonds?

  • Arsenic

  • Nitrogen

  • Phosphorus

  • Antimony


6.

Which of the following statement(s) is/are incorrect for pair of elements Zr-Hf?

  • Both possess same number of valence electrons

  • Both have identical sizes

  • Both have almost identical radii

  • Both of these belong to same period of periodic table


7.

Solubility of which among the following solids in water changes slightly with temperature?

  • KNO3

  • NaNO3

  • KBr

  • NaBr


8.

The colour and magnetic nature of manganate ion (MnO42-) is

  • green, paramagnetic

  • purple, diamagnetic

  • green, diamagnetic

  • purple, paramagnetic


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9.

Which among the following equation represents Arrhenius equation?

  • k = AeEa/ RT

  • k = A . eRT/ Ea

  • k = AeEa/ RT

  • k = AeRT/ Ea


10.

The first law of thermodynamics for isothermal process is

  • q = -W

  • U = W

  • U = qv

  • U = -qv


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