Unit4 The gaseous state qns

# Unit4 The gaseous state qns - 1 THE GASEOUS STATE IDEAL AND...

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1 QUEST TUTORIALS Head Office : E-16/289, Sector-8, Rohini, New Delhi, Ph. 65395439 THE GASEOUS STATE IDEAL AND REAL GASES Select the lettered item which best answers or completes each of the following : 1. Which two of the following are valid statements of Boyle’s law ? (a) If the temperature of a given mass of gas is kept constant, its volume is inversely proportional to the pressure (b) P 1 V 1 = P 2 V 2 (c) The volume of a gas sample is inversely proportional to the pressure, if the temperature is kept constant (d) p/v = k (e) v = kp 2. Which two of the following are valid statements of Charles Law ? (a) k T V = (b) V 1 T 1 = V 2 T 2 (c) the volume of a gas at constant pressure varies directly as the absolute temperature (d) the pressure of a gas varies directly as the absolute temperature 3. By what factor the pressure on a gas be decreased to triple the volume ? (a) 1/3 (b) 1/2 (c) 3/1 (d) ¼ 4. In the equation of state for an ideal gas, PV = nRT, the value of gas constant per degree per mole is (a) 0.0821 litre-atm (b) 8.314 Joules (c) 1.987 cals (d) all of these 5. By means of mercury vapour pump a vacuum of 10 –7 mm Hg is obtained in a certain apparatus. Calculate the number of molecule which still remains in 1 cc. of the apparatus at 27ºC. (a) 23 7 10 0 . 6 300 0821 . 0 1000 1 760 10 × × × × - (b) 23 7 10 0 . 6 300 0821 . 0 1 760 10 × × × - (c) 23 7 10 0 . 6 300 0821 . 0 1 760 10 × × × × - (d) 23 7 10 0 . 6 300 987 . 1 1000 1 760 10 × × × × - 6. 1.35 g of phosphorus vapours occupy 500 ml at 300ºC and 750 mm of Hg pressure. What is the M.W. of phosphorus vapours ? (a) 62 (b) 31 (c) 93 (d) 124 7. The density of a gas is found to be 2.07 g per litre at 30ºC and 2 atm, pressure. Its density at S.T.P. in grams per litre is (a) 4.14 (b) 1.15 (c) 2.30 (d) 2.0 8. The density of a gas is 1.43 g/litre at S.T.P. At what temperature, its density is halved if pressure remains the same ? (a) 273ºC (b) 273 kelvin (c) 27ºC atom (d) none of these 9. The density of O 2 at 25ºC is 1.43 g/litre at 1 atm. Pressure. At what pressure will O 2 have a density twice this value ? Temperature is kept constant. (a) 1.5 atm (b) 3.0 atm (c) 2.0 atm (d) none of these 10. 2.8 g of N 2 , 2.8 g of CO and 4.4 g of CO 2 are found to exert a pressure of 700 torr. The partial pressure of each gas in the mixture is (a) 700 2 1 × (b) 700 4 1 × (c) 700 3 1 × (d) none of these 11. A certain gas effuses through a small opening at a rate exactly one-fifth as great as helium. The M.W. of the gas is (a) 50 (b) 20 (c) 100 (d) 200 12. How many formaldehyde molecules are there in a sample of gas which occupies 11.2 litres at S.T.P. ? (a) 6.0 × 10 23 (b) 3.0 × 10 23 (c) 1.5 × 10 23 (d) none of these 13. A hydride of silicon (V.D. = 46.4) decomposes to give silicon and four times

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2 QUEST TUTORIALS Head Office : E-16/289, Sector-8, Rohini, New Delhi, Ph. 65395439 its volume of hydrogen gas. The formula of hydride is (a) SiH 4 (b) Si 2 H 6 (c) Si 3 H 8 (d) Si 4 H 10 14. The product, PV, is a unit of
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## Unit4 The gaseous state qns - 1 THE GASEOUS STATE IDEAL AND...

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