The amount of the heat released when 20 mL 0.5 M NaOH is mixed wi

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 Multiple Choice QuestionsMultiple Choice Questions

271.

Commercial sample of H2O2 is labeled as 10 V. Its % strength is nearly

  • 3

  • 6

  • 9

  • 12


272.

The system that contains the maximum number of atoms is

  • 4.25 g of NH3

  • 8 g of O2

  • 2g of H2

  • 4g of He


273.

The volume of ethyl alcohol ( density 1.15 g/cc) that has to be added to prepare 100 cc of 0.5 M ethyl alcohol solution in water is 

  • 1.15 cc

  • 2 cc

  • 2.15 cc

  • 2.30 cc


274.

Which one of the following is wrong about molecularity of a reaction?

  • It may be whole number or fractional

  • It is calculated from reaction mechanism

  • It is the number of molecules of the reactants taking part in a single step chemical reaction

  • It is always equal to the order of elementary reaction


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275.

The amount of the heat released when 20 mL 0.5 M NaOH is mixed with 100 mL 0.1 M HCl is × kJ. The heat of neutralisation is

  • -100 x kJ/mol

  • -50 x kJ/mol

  • + 100 x kJ/mol

  • +50 x kJ/mol


A.

-100 x kJ/mol

Millimoles or milliequivalents of NaOH = 20 × 0.5 = 10

                               Millimoles of HCl = 100 × 0.1 = 10

Therefore,
NaOH + HCl → NaCl + H2O

Thus, heat released when 10 milliequivalents of HCl are neutralised by 10 millimoles of NaOH = x kJ.

Heat of neutralisation is the heat released when 1 equivalent of HCl is neutralised by 1 equivalent of NaOH.

 neuH = -x10 × 10-3 or -100 × kJ/mol


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276.

2 g of metal carbonate is neutralised completely by 100 mL of 0.1 N HCl. The equivalent weight of metal carbonate is

  • 50

  • 100

  • 150

  • 200


277.

If the molecular wt. of Na2SOand I2 are M1 and Mrespectively then what will be the equivalent weight of Na2SO3 and I2 in the following reaction?

2S2O32- + I2 → S4O62- + 2I-

  • M1, M2

  • M1, M2 /2

  • 2M1, M2

  • M1, 2M2


278.

The normality of 30 volume H2O2 is

  • 2.678 N

  • 5.336 N

  • 8.034 N

  • 6.685 N


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279.

The weight of oxalic acid that will be required to prepare a 1000 mL (N/20) solution is

  • 126/100 g

  • 63/40 g

  • 63/20 g

  • 126/20 g


280.

Gaseous benzene reacts with hyodrogen gas in presence of a nickel catalyst to form gaseous cyclohexane according to the reaction, 

C6H6 (g) + 3H2 (g) → C6H12 (g)

A mixture of C6H6 and excess H2 has a pressure of 60 mm of Hg in an unknown volume. After the gas had been passed over a nickel catalyst and all the benzene converted to cyclohexane, the pressure of the gas was 30 mm of Hg in the same volume at the same temperature. The fraction of C6H6 (by volume) present in the original volume is

  • 1/3

  • 1/4

  • 1/5

  • 1/6


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