5.0 g of sodium hydroxide (molar mass 40 g mol-1) is dissolved in

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 Multiple Choice QuestionsMultiple Choice Questions

71.

The volume of neon gas in cm3 at STP having the same number of atoms as that present in 800 mg of Ca is (At. mass : Ca = 40 g mol-1, Ne = 20 g mol-1)

  • 448

  • 896

  • 224

  • 112


72.

How many molecules of CO2 are formed when one milligram of 100% pure CaCO3 is treated with excess hydrochloric acid?

  • 6.023 × 1023

  • 6.023 × 1018

  • 6.023 × 1021

  • 6.023 × 1022


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73.

5.0 g of sodium hydroxide (molar mass 40 g mol-1) is dissolved in little quantity of water and the solution is diluted upto 100 ml. What is the molarity of the resulting solution?

  • 0.1 mol dm-3

  • 1.0 mol dm-3

  • 0.125 mol dm-3

  • 1.25 dm-3


D.

1.25 dm-3

Given, W (mass of solute) = 5.0 g

m (molar mass of solute) = 40 g mol-1

volume = 100 mL

molarity is given as,

M =moles of soluteVolume of solution (in l)M= W × 1000m × Volume of solution (in ml)M=5.0 g × 100040 × 100 = 1.25 mol dm-3


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74.

The mole fraction of methanol is in 4.5 molal aqueous solution is

  • 0.250

  • 0.125

  • 0.100

  • 0.075


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75.

0.02 mole of [Co(NH3)5Br]Cl2 and 0.02 mole of [Co(NH3)5Cl]SO4 are present in 200 cc of a solution X. The number of moles of the precipitates Y and Z that are formed when the solution X is treated with excess barium chloride are respectively.

  • 0.02, 0.02

  • 0.01, 0.02

  • 0.02, 0.04

  • 0.04, 0.02


76.

The maximum prescribed concentration of cadmium in drinking water in ppm is

  • 0.05

  • 3

  • 2

  • 0.005


77.

A 100% pure sample of a divalent metal carbonate weighing 2 g on complete thermal decomposition releases 448 cc of carbon dioxide at STP. The equivalent mass of the metal is

  • 40

  • 20

  • 28

  • 12


78.

A mixture of ethane and ethene occupies 41 L at 1 atm and 500 K. The mixture reacts completely with 103mole of O2 to produce CO2 and H2O. The mole fraction of ethane and ethene in the mixture are respectively (R = 0.082 L atm K-1 mol-1)

  • 0.50, 0.50

  • 0.75, 0.25

  • 0.67, 0.33

  • 0.25, 0.75


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79.

Molar heat capacity of aluminium is 25 JK-1 mol-1. The heat necessary to raise the temperature of 54 g of aluminium (atomic mass 27 g mol-1) from 30°C to 50°C is

  • 1.5 kJ

  • 0.5 kJ

  • 1.0 kJ

  • 2.5 kJ


80.

How much time (in hours) would it take to distribute one Avogadro number of wheat grains, if 1020 grains are distributed each second?

  • 0.1673

  • 1.673

  • 16.73

  • 167.3


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