Stoichiometry

341. The value of the gas-law constant 'R' is 1.987

1. kcal/kg-mole.°C
2. Btu/lb-mole.°R
3. kcal/kg-mole.°K
4. Both (B) & (C)

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342. The value of Trouton's ratio (λ_b/T_b) for a number of substances is 21 (where, λb = molal that of vaporisation of a substance at its normal boiling point, KCal/kg. mole and T_b = normal boiling point, °K). The Kistyakowsky equation is used for calculation of Trouton's ratio of _________ liquids.

1. Polar
2. Non-polar
3. Both (A) & (B)
4. Neither (A) nor (B)

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343. The vapor pressure of a substance, at its melting point, is _________ in the solid state as compared to that in the liquid state.

1. Less
2. More
3. Same
4. Either (A) or (B); depends on the nature of the substance

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344. The vapor pressure of liquids (having similar chemical nature) at any specified temperature _________ with increasing molecular weight.

1. Increases
2. Decreases
3. Remains unchanged
4. Increases linearly

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345. The vapor pressure of liquids of similar chemical nature at any particular temperature _________ with increase in the molecular weight.

1. Increases
2. Decreases
3. Remains unchanged
4. Either (A) or (B); depends on the liquid

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346. The vapor pressure of the solvent decreased by 10 mm Hg, when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent, if the decrease in vapor pressure of the solvent is required to be 20 mm Hg?

1. 0.2
2. 0.1
3. 0.4
4. 0.6

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347. The vapor pressure of water at 100°C is

1. 100 N/m²
2. 76 cms of Hg
3. 13.6 cms of Hg
4. 760 mm wc

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348. The vapor pressures of benzene and toluene are 3 and 4/3 atmospheres respectively. A liquid feed of 0.4 moles of benzene and 0.6 moles of toluene is vaporised. Assuming that the products are in equilibrium, the vapor phase mole fraction of benzene is

1. 0.4
2. 0.6
3. 0.8
4. 0.2

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349. The vapour pressure of water is given by, in P_sat = A - (5000/T), where A is a constant, P_sat is the vapour pressure in atm. and T is the temperature in K. The vapor pressure of water in atm. at 50°C is approximately

1. 0.07
2. 0.09
3. 0.11
4. 0.13

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350. The viscosity of water at room temperature may be around one

1. Centipoise
2. Poise
3. Stoke
4. Both (B) & (C)

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