States of Matter Solid, Liquid and Gas MCQ Questions & Answers in Physical Chemistry | Chemistry
Learn States of Matter Solid, Liquid and Gas MCQ questions & answers in Physical Chemistry are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.
131.
The values of van der Waals constant ‘a’ for the gases $${O_2},{N_2},N{H_3}$$ and $$C{H_4}$$ are 1.360, 1.390, 4.170 and 2.253 $${L^2}\,atm\,mo{l^{ - 2}}$$ respectively. The gas which can most easily be liquified is:
A
$${O_2}$$
B
$${N_2}$$
C
$$N{H_3}$$
D
$$C{H_4}$$
Answer :
$$N{H_3}$$
$$'a’$$ is directly related to forces of attraction. Hence greater the value of $$'a’,$$ more easily the gas is liquified.
132.
According to kinetic theory of gases, for a diatomic molecule
A
the pressure exerted by the gas is proportional to mean velocity of the molecule
B
the pressure exerted by the gas is proportional to the root mean velocity of the molecule
C
the root mean square velocity of the molecule is inversely proportional to the temperature
D
the mean translational kinetic energy of the molecule is proportional to the absolute temperature.
Answer :
the mean translational kinetic energy of the molecule is proportional to the absolute temperature.
133.
In the fluorite structure, the coordination number of $$C{a^{2 + }}\,ion$$ is
A
4
B
6
C
8
D
3
Answer :
8
In fluorite structure each $$C{a^{2 + }}\,ion$$ is surrounded by eight $${F^ - }\,ions.$$ Thus, the coordination number of $$C{a^{2 + }}$$ is eight.
134.
The molecular velocities of two gases at the same temperature are $${u_1}$$ and $${u_2}$$ and their masses are $${m_1}$$ and $${m_2}$$ respectively. Which of the following expressions are correct?
A
$$\frac{{{m_1}}}{{u_1^2}} = \frac{{{m_2}}}{{u_2^2}}$$
B
$${m_1}{u_1} = {m_2}{u_2}$$
C
$$\frac{{{m_1}}}{{{u_1}}} = \frac{{{m_2}}}{{{u_2}}}$$
135.
With which one of the following elements silicon should be doped so as to give $$p$$ - type of semiconductor?
A
Germanium
B
Arsenic
C
Selenium
D
Boron
Answer :
Boron
$$p$$ - type of semiconductor are obtained by doping silicon or germanium with elements of group 13 like $$B,$$ $$Al,$$ $$Ga$$ or $$In$$ so silicon is doped with boron.
136.
When does a gas deviate the most from its ideal behaviour?
A
At low pressure and low temperature
B
At low pressure and high temperature
C
At high pressure and low temperature
D
At high pressure and high temperature
Answer :
At high pressure and low temperature
At high pressure and low temperature, gaseous atoms or molecules get closer to each other and van der Waal forces operates.
So molecules or atoms start attracting each other. Hence a gas deviate the most from its ideal behaviour. While in ideal behaviour we consider that gaseous molecules do not attract each other, i.e., there is no intermolecular forces of attraction.
137.
Positive deviation from ideal behaviour takes place because of
A
Molecular interaction between atoms and $$\frac{{PV}}{{nRT}} > 1$$
B
Molecular interaction between atoms and $$\frac{{PV}}{{nRT}} < 1$$
C
Finite size of atoms and $$\frac{{PV}}{{nRT}} > 1$$
D
Finite size of atoms and $$\frac{{PV}}{{nRT}} < 1$$
Answer :
Finite size of atoms and $$\frac{{PV}}{{nRT}} > 1$$
For positive deviation : $$PV = nRT + nPb$$
$$ \Rightarrow \frac{{PV}}{{nRT}} = 1 + \frac{{Pb}}{{RT}}$$
Thus, the factor nPb is responsible for increasing the $$PV$$ value, above ideal value. $$b$$ is actually the effective volume of molecule. So, it is the finite size of molecules that leads to the origin of $$b$$ and hence positive deviation at high pressure.
138.
Read the following statements and identify the incorrect statement.
A
Volume of one mole of a gas at critical temperature is called molar volume.
B
Pressure of a gas at critical temperature is called critical pressure.
C
The critical temperature, pressure and volume are called critical constants.
D
Critical temperature is the highest temperature at which a gas can exist as liquid, above this temperature it is a gas.
Answer :
Volume of one mole of a gas at critical temperature is called molar volume.
Volume of one mole of a gas at $$STP$$ is called its molar volume.
139.
Correct gas equation is
A
$$\frac{{{V_1}{T_2}}}{{{p_1}}} = \frac{{{V_2}{T_1}}}{{{p_2}}}$$
B
$$\frac{{{p_1}{T_1}}}{{{V_1}}} = \frac{{{p_2}{V_2}}}{{{T_2}}}$$
C
$$\frac{{{p_1}{V_1}}}{{{p_2}{V_2}}} = \frac{{{T_1}}}{{{T_2}}}$$
D
$$\frac{{{V_1}{V_2}}}{{{T_1}{T_2}}} = {p_1}{p_2}$$
If temperature, volume and pressure of fixed amount ( say $$n$$ mole ) of a gas vary from $${T_1},{V_1}$$ and $${p_1}$$ to $${T_2},{V_2}$$ and $${p_2}$$ respectively. Then, ideal gas equation for two states can be written as
$$\eqalign{
& {p_1}{V_1} = nR{T_1} \cr
& {\text{or}}\,\,\frac{{{p_1}{V_1}}}{{{T_1}}} = nR\,\,\,...{\text{(i)}} \cr
& {p_2}{V_2} = nR{T_2} \cr
& {\text{or}}\,\,\frac{{{p_2}{V_2}}}{{{T_2}}} = nR\,\,\,...{\text{(ii)}} \cr
& {\text{On combining Eqs}}{\text{. (i) and (ii), we get}} \cr
& \frac{{{p_1}{V_1}}}{{{T_1}}} = \frac{{{p_2}{V_2}}}{{{T_2}}} \cr
& {\text{or}}\,\,\,\frac{{{p_1}{V_1}}}{{{p_2}{V_2}}} = \frac{{{T_1}}}{{{T_2}}} \cr} $$
So, it called combined gas equation.
Hence, (C) answer is correct.
140.
Cyclopropane and oxygen at partial pressures 170 $$torr$$ and 570 $$torr$$ respectively are mixed in a gas cylinder. What is the ratio of the number of moles of cyclopropane to the number of moles of oxygen $$\left( {\frac{{n{C_3}{H_6}}}{{n{O_2}}}} \right)?$$
A
$$\frac{{170 \times 42}}{{570 \times 32}} = 0.39$$
B
$$\frac{{\frac{{170}}{{42}}}}{{\left( {\frac{{170}}{{42}} + \frac{{570}}{{32}}} \right)}} \approx 0.19$$