Chemistry - State of Matter : Gaseous and Liquid States
Exam Duration: 45 Mins Total Questions : 30
The minimum pressure required to compress \(500\ dm^3\) of air at 1 bar to \(200\ dm^3\) at \(30^o\ C\) is
- (a)
1 bar
- (b)
2.5 bar
- (c)
5 bar
- (d)
5.8 bar
A student forgot to add the reaction mixture to the round bottomed flask and \(27^oC\) but instead he/she placed the flask on the flame. After a lapse of time, he realised his mistake and using a pyrometer he found the temperature of the flask was \(477^oC\). What fraction of air would have been expelled out?
- (a)
1.1
- (b)
0.8
- (c)
0.65
- (d)
0.6
Which of the following graphs is not a straight line for an ideal gas?
- (a)
V versus T (n and p constant)
- (b)
T versus p (n and V constant)
- (c)
p versus 1 / V (n and T constant)
- (d)
n versus 1 / p (V and T constant)
A sample of a unknown gas is placed in a 2.5 L bulb at pressure of 360 torr and at a temperature of \(22.5^oC\) and is found to weigh 1.6616 g. What is the molecular weight of the gas?
- (a)
80 g
- (b)
64 g
- (c)
55 g
- (d)
34 g
The SI unit for the quantity \(pV^2T^2/n\) is
- (a)
\(Nm^2\ K\ mol^{-1}\)
- (b)
\(Nm^4\ K\ mol^{-1}\)
- (c)
\(Nm^4\ K^2\ mol^{-1}\)
- (d)
\(N^{-1}m^2\ K^2\ mol^{-1}\)
The kinetic molecular theory of gases predicts pressure to rise as the temperature of a gas increases. It is because
- (a)
gas molecules collide more frequently with the container walls
- (b)
gas molecules collide less frequently
- (c)
gas molecules have less kinetic energy
- (d)
gas molecules collide less energetically with container walls
As the temperature increases, average kinetic energy of molecules increases. What would be the effect of increase of temperature on pressure provided the volume is constant?
- (a)
Increases
- (b)
Decreases
- (c)
Remains same
- (d)
Becomes half
If the values of van der Waals' constant 'a' for \(O_1.N_2,NH_3\) and \(CH_4\) gases are \(1.360, 1.390, 4.170\) and \(2.253\ L^3\) atm \(mol^{-2}\) respectively. The gas which can most easily be liquefied is
- (a)
\(O_2\)
- (b)
\(N_2\)
- (c)
\(NH_3\)
- (d)
\(CH_4\)
A person living in Shimla observed that cooking food without using pressure cooker takes more time. The reason for this observation is the at high altitude.
- (a)
pressure increases
- (b)
temperature decreases
- (c)
pressure decreases
- (d)
temperature increases
Match of the following and choose the correct option.
Column I | Column II |
A. Unit of R | p. \(JK^{-1}\ mol^{-1}\) |
B. Unit of surface tension | q. dyne \(cm^{-1}\) |
C. Unit of coefficient of viscosity | r. \(atmL^2\ mol^{-2}\) |
D. Unit of van der Waals' constant (a) | s. dyne \(cm^{-2}\ s\) |
- (a)
A B C D q p s r - (b)
A B C D s q p r - (c)
A B C D p q s r - (d)
A B C D q s p r
Increase in kinetic energy can overcome intermolecular forces of attraction. How will the viscosity of liquid be affected by the increase in temperature?
- (a)
Increase
- (b)
No effect
- (c)
Decrease
- (d)
No regular pattern wil be followed
Natural hydrogen consists of 80% \(H_2\) and 20% \(D_2\) by mass. The number of ideal diffusion steps required to produce 94.11% \(H_2\) from mixture are
- (a)
12
- (b)
8
- (c)
6
- (d)
4
20% \(N_2O_4\) molecules are dissociated in a sample of gas at \(27^oC\) and 760 torr pressure. What is the density of equilibrium mixture?
- (a)
\(3.1\ g\ L^{-1}\)
- (b)
\(6.2\ g\ L^{-1}\)
- (c)
\(9.3\ g\ L^{-1}\)
- (d)
\(12.4\ g\ L^{-1}\)
A mixture of hydrogen and helium is prepared in such a way that the number of collisions on the wall per unit time by molecules of each gas is same. The gas which has higher concentration is
- (a)
hydrogen
- (b)
helium
- (c)
both have same concentration
- (d)
it cannot be determined
When an ideal gas undergoes unrestrained expansion, no cooling occurs because the molecules
- (a)
are above inversion temperature
- (b)
collide without loss of energy
- (c)
do work equal to loss in kinetic energy
- (d)
exert no attractive forces on each other.
For two gases A and B with molecular weights \(M_A\) and \(M_B\), it is observed that at temperature T, the average velocity of A is equal to the RMS velocity of A is equal to the RMS velocity of B. At what conditions, the average velocity of A can be made equal to the average velocity of B?
- (a)
A is lowered to a temperature \(T_2={3\pi\over 8T}\)
- (b)
B is lowered to a temperature \(T_2=8T/3\pi\)
- (c)
A is lowered to a temperature \(T_2={8\pi\over 3\pi}\)
- (d)
B is lowered to a temperature \(T_2={3\pi\over 8T}\)
If the most probable speed is represented by mps and fraction of molecules possessing this speed by f, then which option is correct with the increase in temperature?
- (a)
Both mps and f will decrease
- (b)
Both mps and f will increase
- (c)
mps will increase but f will decrease
- (d)
mps will decrease but f will increase
The wrong statement among the following is
- (a)
A gas shows negative deviation when long range attractive
- (b)
The gas would exert pressure \(p+{an^2\over V^2}\) if it was ideal
- (c)
At \(270^oC,\) the intercept of pV vs p isotherm of ideal gas is equal to 24.6 L atm \(mol^{-1}\)
- (d)
Above their respective Boyle's temperature, \(N_2\) shows throughout positive deviation \((Z>1)\) while \(O_2\) shows negative deviation \((Z<1)\) followed by positive deviation \((Z>1)\)
At moderate pressure, the compressibility factor of a particular gas is given by \(Z=1+0.34\ p-{170\ p\over T};\) where p is in bar and T is in kelvin. What will be the Boyle's temperature?
- (a)
100 K
- (b)
380 K
- (c)
500 K
- (d)
680 K
When r, p and M represent rate of diffusion, pressure and molecular mass, respectively, then the ratio of the rates of diffusion \((r_A/r_B)\) of two gases A and B is given as
- (a)
\(({p_A\over p_B})^{1/2}({M_A\over M_B})\)
- (b)
\(({p_A\over p_B})({M_A\over M_B})^{1/2}\)
- (c)
\(({p_A\over p_B})^{1/2}({M_B\over M_A})\)
- (d)
\(({p_A\over p_B})({M_A\over M_B})^{1/2}\)
For gaseous state, if most probable speed is denoted by C*, average speed by C and mean square speed by C, then for a large number of molecules, the ratios of these speed are
- (a)
\(C*:\overline C:C=1.225 : 1.128 : 1\)
- (b)
\(C*:\overline C:C=1.128 : 1.225 : 1\)
- (c)
\(C*:\overline C:C=1:1.128 : 1.225\)
- (d)
\(C*:\overline C:C=1 : 1.225 : 1.128\)
If Z is a compressibility factor, van der Waals' equation at low pressure can be written as
- (a)
\(z=1+{RT\over pb}\)
- (b)
\(z=1-{a\over VRT}\)
- (c)
\(z=1-{pb\over RT}\)
- (d)
\(z=1+{pb\over RT}\)
The compressibility factor for a real gas at high pressure is
- (a)
\(1+RT/pb\)
- (b)
\(1\)
- (c)
\(1+pb/RT\)
- (d)
\(1-pb/RT\)
a and b are van der Waals' constants for gases. Chlorine is more easily liquefied then ethane because
- (a)
a and b for \(Cl_2>\)a and b for \(C_2H_6\)
- (b)
a and b for \(Cl_2<\)a and b for \(C_2H_6\)
- (c)
a for \(Cl_2<\) a for \(C_2H_6\) but b for \(Cl_2>b\) for \(C_2H_6\)
- (d)
a for \(Cl_2>\) a for \(C_2H_6\) but b for \(Cl_2 for \(C_2H_6\)
The molecular velocity of any gas is
- (a)
inversely proportional to the square root of temperature
- (b)
inversely proportional to absolute temperature
- (c)
directly proportional to square of temperature
- (d)
directly proportional to square root of temperature
If \(10^{-4} dm^3 \) of water is introduced into a \(1.0 dm^3\) flask at 300 K, how many moles of water are in the vapour phase when equilibrium is established? [Given, vapour pressure of \(H_2O\) at 300 K is 3170 Pa, R = 8.314 \(JK^{-1}\ mol^{-1}\)]
- (a)
\(5.56\times 10^{-3}\ mol\)
- (b)
\(1.53\times 10^{-2}\ mol\)
- (c)
\(4.46\times 10^{-2}\ mol\)
- (d)
\(1.27\times 10^{-3}\ mol\)
Equal masses of methane and oxygen are mixed in an empty container at \(25^oC.\) The fraction of the pressure exerted by oxygen is
- (a)
\(2\over 3\)
- (b)
\({1\over 3}\times {273\over 298}\)
- (c)
\(1\over 3\)
- (d)
\(1\over 2\)
If helium and methane are allowed to diffuse out of the container under the similar conditions of temperature and pressure, then ratio of rate of diffusion of helium to methane is
- (a)
2.0
- (b)
1.0
- (c)
0.5
- (d)
4.0
As the temperature is raised from \(20^oC\) to \(40^oC\), the average kinetic energy of neon atoms changes by a factor of which of the following?
- (a)
1/2
- (b)
\(\sqrt{3113/293}\)
- (c)
\(313/293\)
- (d)
2