Stoichiometry

281. The activity co-efficient of a solution, which accounts for the departure of liquid phase from ideal solution behaviour

1. Measures the elevation in boiling point
2. Is not dependent on the temperature
3. Is a function of the liquid phase composition
4. Measures the depression in freezing point

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282. The amount of Zn (atomic weight = 65) required to form 224 c.c. of H₂ at N.T.P. on treatment with dilute H₂SO4will be _________ gm.

1. 0.065
2. 0.65
3. 6.5
4. 65

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283. The atomic heat capacities of all solid elements _________ with decrease in temperature.

1. Increases
2. Decreases
3. Remains unchanged
4. Approach zero at 0°C

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284. The atomic weight of helium is 4 times that of hydrogen. Its diffusion rate as compared to hydrogen will be _________ times.

1. 43862
2. 4
3. √2
4. 43922

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285. The average translational kinetic energy with which a gas molecule is endowed is dependent on its

1. Nature
2. Size
3. Absolute temperature
4. All (A), (B) & (C)

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286. The boiling points for pure water and pure toluene are 100°C and 110.6°C respectively. Toluene and water are completely immiscible in each other. A well agitated equimolar mixture of toluene and water are prepared. If, at a total pressure of one standard atm. exerted by the vapours of water and toluene, the mole fraction of water X^w in the vapour phase satisfies

1. 0 < X_w < 0.5
2. X_w = 0.5
3. 0.5 < X_w < 1.0
4. X_w = 1.0

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287. The boiling points for pure water and pure toluene are 100°C and 110.6°C respectively. Toluene and water are completely immiscible in each other. A well agitated equimolar mixture of toluene and water are prepared. The temperature at which the above mixture will exert a pressure of one standard atm. is

1. Less than 100°C
2. 100°C
3. Between 100 and 110°C
4. 110.6°C

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288. The chemical nature of an element is independent of

1. Its atomic number
2. The number of protons or electrons present in it
3. The number of neutrons present in it
4. None of these

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289. The combustion equations of carbon and carbon monoxide are as follows: C + O₂ = CO₂, ΔH = - 394 kJ/kg .mole CO + ½ O₂ = CO₂, ΔH = - 284.5 kJ/kg. mole. The heat of formation of CO is _________ kJ/kg. mole.

1. -109.5
2. 109.5
3. 180
4. 100

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290. The crystallisation of a solute from a solution may be done by

1. Removal of pure solvent by evaporation
2. Change of temperature thereby causing super-saturation
3. Changing the nature of the system by the addition of a more soluble material
4. All (A), (B) & (C)

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