Air is filled at 60°C in a vessel of open mouth. The vessel is heated to a temperature T so that 1/4th part of the air escapes. Assuming the volume of vessel remaining constant, the value of T is (in °C).
M1 = M,
T1 = 60 + 273 = 333 K
(as 1/4 th part of air escapes)
If pressure and volume of gas remain constant then
MT = constant
⇒ T2 = 444K = 171°C
The correct answer is: 171
A gas at a certain volume and temperature has pressure 75cm of Hg. If the mass of the gas is doubled at the same volume and temperature, its new pressure in units of cm of Hg level?
At constant volume and temperature, if mass of gas is doubled, then pressure will become twice.
The correct answer is: 150
A flask contains 10-3 m3 gas. At a temperature, the number of molecule of oxygen are 3 × 1022 . The mass of an oxygen molecule is 5.3 × 10-26 kg and at that temperature, the rms velocity of molecules is 400 m/s. The pressure (in 104 N/m2 ) of the gas in the flask is.
p = 8.48 × 104 N/m2
The correct answer is: 8.84
The root means square speed of hydrogen molecules at 300 K is 1930 m/s. Then the root mean square of oxygen molecules at 900 K will be (in m/s).
= 836 m/s
The correct answer is: 836
At which of the following temperature would the molecules of a gas have twice the average kinetic energy they have at 20°C (in °C)
E ∝ T
⇒ T2 = 293 × 2 = 586 K
⇒ T2 = 313 °C
The correct answer is: 313
The speeds of 5 molecules of a gas (in arbitrary units) are as follows : 2, 3, 4, 5, 6. The root mean square speed for these molecules is.
The correct answer is: 4.24
Two identical glass bulbs are inter connected by a thin glass tube. A gas is filled in these bulbs at NTP. If one bulb is placed in ice and another bulb is placed is hot bath, then the pressure of the gas becomes 1.5 times. the temperature of hot bath will be (in °C).
Quantity of gas in these bulbs is constant i.e.
Initial number of moles is both bulb = Final Number of moles.
⇒ T = 819 K = 546°C
The correct answer is: 546
Hydrogen gas is filled in a balloon at 20°C. If temperature is made 40°C, pressure remaining same, what fraction of hydrogen will come out?
As V ∝ T
Fraction of gas coming out =
The correct answer is: 0.07
A closed vessel contains 8gm of oxygen and 7gm of nitrogen. The total pressure is 10atm at a given temperature. If now oxygen is absorbed by introducing a suitable absorbent the pressure of the remaining gas (in atm) will be?
From Dalton’s law, find pressure of mixture of nitrogen and oxygen
p = p1+ p2
when oxygen is absorbed, then for nitrogen let pressure be p
From (1) and (2) p = 5 atm.
The correct answer is: 5
A flask is filled with 13 gm of an ideal gas at 27°C and its temperature is raised to 52°C. The mass of the gas that has to be released to maintains the temperature of the gas in the flask at 52°C and the pressure remaining the same is (in gm).
pV ∝ Mass of gas x Temperature
In this problem, pressure and volume remains constant so M1 T1 = M2 T2 = constant
i.e., mass of the gas released from the flask = 13 – 12 = 1gm.
The correct answer is: 1