Order intermolecular forces of attraction are negligible

Order intermolecular forces of attraction are negligible
82. The figure shows a narrow tube kept horizontally with air column of 10 cm in length trapped by 8 cm of mercury
column. The pressure of air outside is 0.96 atm. [1 atm = 76 cm of Hg]. If the tube is kept in a slanting position at 45q
to the vertical with the open end up, Calculate the length of the trapped column of air
10 cm
air column mercury
column
0.96 atm
pressure
8 cm
(a) 8.28 cm (b) 7.28 cm (c) 9.28 cm (d) 7.82 cm
83. A mixture of N2
O4(g) and NO2(g) under dissociation equilibrium N2
O4(g) 2NO2(g) has a degree of dissociation =
0.6 at temperature TK. The mean molar mass of the mixture is
(a) 75.5 g mol1 (b) 67.5 g mol1 (c) 50.7 g mol1 (d) 57.5 g mol1
84. Two cylinders A and B contain the same gas at the same temperature. The pressure and volume of A are both twice
those of B. Then the ratio of the number of molecules of A and B is
(a) 1 : 4 (b) 4 : 1 (c) 2 : 1 (d) 1 : 2
85. An electronic tube of volume 200 ml was sealed off during manufacture at a pressure 1.8 u 105
torr. At T = 300 K,
calculate the number of molecules contained in it
(a) 5.8 u 1013 (b) 1.16 u 1014 (c) 2.9 u 1014 (d) 2.9 u 1013
86. A 10 litre cylinder of oxygen at 4 atm pressure at 17qC developed a leak. When the leak was repaired the remaining
oxygen had a pressure of 3 atm. Calculate the number of moles of oxygen escaped
(a) 0.63 (b) 0.515 (c) 0.42 (d) 0.71
87. The density of oxygen gas at 293 K and 3 atm pressure is nearly
(a) 3.5 g L1 (b) 2.9 g L1 (c) 4 g L1 (d) 4.5 g L1
88. A stony mass believed to be a meteorite contained, as revealed by analysis, 36Ar atoms to the extent of 2 u 107
litre at
STP per kg of the mass. Calculate the number of atoms of Ar, per kg of the mass
(a) 5.4 u 1015 (b) 4.5 u 1014 (c) 4.4 u 1016 (d) 6.5 u 1016
89. A gas cylinder contains 11.6 moles of O2
gas at 298 K. The cylinder has a volume of 9.43 litres. The cylinder is now
heated to 75qC and then a valve is opened to allow the oxygen to escape. The final temperature and pressure are 75qC
and 1 atm. Calculate the mass of oxygen that has escaped
(a) ~342 g (b) ~360 g (c) ~412 g (d) ~312 g
90. Krypton at 500 torr in a 250 ml container and helium at 950 torr in a 450 ml flask both at the same temperature are
mixed by opening a stop cock in a narrow tube connecting the containers. Calculate the total final pressure.
(a) 690 torr (b) 670 torr (c) 720 torr (d) 790 torr
91. Calculate the pressure of H2
S gas in atm at 27qC if the density is 2.76 g L1 (At.wt. of S = 32) is
(a) 2 atm (b) 1.5 atm (c) 2.25 atm (d) 2.5 atm
92. At a certain altitude above the surface of the earth (mean sea level) the temperature and pressure of air are 100qC
and 5 u 107
torr. Calculate the density assuming the density of air at STP = 1. Assume also that the composition of
the air is uniform throughout
(a) 108
(b) ~109
(c) 5 u 108
(d) 9 u 109
93. Three volatile (gaseous) compounds of a certain elements have densities of 6.75 g L1
, 9.56 g L1
and 10.08 g L1
respectively at STP. The three compounds contain 96%, 33.9% and 96.4% by weight of the element (Assume ideal behaviour
of the gases) Suggest an atomic weight for the element
(a) 145 (b) 218 (c) 54.4 (d) 72.5