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 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
He atom is two times heavier than a hydrogen molecule. At 298 K, the average kinetic energy of the atom is
- (a)
two times that of a hydrogen
- (b)
same as that of a hydrogen molecule
- (c)
one fourth that of a hydrogen molecule
- (d)
half that of a hydrogen molecule
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
For a monoatomic gas, kinetic energy is E. Its relation with \(V_{rmx}\) velocity is
- (a)
\(v_{rms}=({2E\over m})^{1/2}\)
- (b)
\(v_{rms}=({E\over m})^{1/2}\)
- (c)
\(v_{rms}=({E\over 2m})^{1/2}\)
- (d)
\(v_{rms}=({4E\over 3m})^{1/2}\)
The ratio of root mean square velocity to average velocity of a gas molecule at a particular temperature is
- (a)
1 : 1.086
- (b)
2 : 1.86
- (c)
1.086 : 1
- (d)
2.086 : 1
A gas obeys the equation of state \(p(V-b)=RT\) where, b is a constant. The slope for an isochore will be
- (a)
negative
- (b)
zero
- (c)
\({R\over (V-b)}\)
- (d)
\(R\over P\)
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)
\(CH_4\)
At a high pressure, van der Waals' equation reduces to
- (a)
\(({p+{an^2\over V^2}})\ V=nRT\)
- (b)
\(p(V-b)=nRT+pV\)
- (c)
\(pV=nRT\)
- (d)
\(P(V-nb)=nRT\)
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
Six grams each of the following gases at \(87^oC\) and 750 mm pressure are taken. Which of the following has the least volume?
- (a)
HF
- (b)
HCl
- (c)
HBr
- (d)
HI
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
If excess of \(F_2\ (g)\) reacts at \(150^o\ C\) and 1.0 atm pressure with \(Br_2(g)\), a compound \(BrF_n\) is formed. If 423 mL of \(Br_2(g)\) at the same temperature and pressure produces 4.2 g of \(BrF_n,\) the value of n is \(({Br=80, F=19})\)
- (a)
1
- (b)
3
- (c)
5
- (d)
7
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
At higher temperature, greater number of molecules have high velocity.
- (a)
kinetic energy of A > kinetic energy of B
- (b)
the number of molecules of methane is four times that of \(O_2\)
- (c)
pressure in flask A < pressure in flask B
- (d)
molecules in flask B are twice more than that in flask A
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.
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 \((Z>1)\)
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)
\(C*:\overline C:C=1 : 1.225 : 1.128\)
The term that corrects for the attractive forces present in a real gas in the van der Waals' equation is
- (a)
nb
- (b)
\(n^2a/V^2\)
- (c)
\(-({n^2a/V^2})\)
- (d)
- nb
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
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