Chemistry - States of Matter
Exam Duration: 45 Mins Total Questions : 30
Real gases approach ideal behaviour at
- (a)
high temperature and low pressure
- (b)
low temperature and low pressure
- (c)
high temperature and high pressure
- (d)
critical temperature
At a given temperature, volume, are pressure of a gas obeying van der Waals equation is
- (a)
less than that of an ideal gas
- (b)
more than trhat of an ideal gas
- (c)
more or less depending on the nature of gas
- (d)
equal to that of an ideal gas
The temperature of a certain mass of a gas was increased from \({ 40 }^{ \circ }C\ to\ {41 }^{ \circ }C\) at constant pressure. The volume of the gas
- (a)
will increase by 1/273 of its volume at 273 K
- (b)
will increase by1/273of its volume at \({ 40 }^{ \circ }C\)
- (c)
will remain constant
- (d)
will increase, but the increase in volume cannot be predicted
Helium atoms is two times heavier than a hydrogen molecule. At 300 K, the average K.E. of a helium atom is
- (a)
equal to that of hydrogen atom
- (b)
half that of hydrogen molecule
- (c)
same as that of hydrogen molecule
- (d)
two times that of hydrogen molecule
Two flasks A and B each 500 ml capacity contain helium and hydrogen respectively at \({ 27 }^{ \circ }C\) and 1 atmospheric pressure. The flask A contains
- (a)
the same number of atoms as in B
- (b)
the same weight of the gas as in B
- (c)
double the number of atoms as in B
- (d)
half the number of atoms as in B
A mixture of three gases A (density 0.90), B (density 0.178) and C (density 0.42) are enclosed in avessel at constant temperature. When the equilibrium is established
- (a)
the gas A will be at the top of the vessel
- (b)
the gas B will be at the top of the vessel
- (c)
the gas C will be at the top of the vessel
- (d)
the gases will mix homogenously throughout the vessel
The correct representation of van der Waal's equation is
- (a)
PV = RT
- (b)
(P+a/V2)(V-b) = RT
- (c)
(P-a/V2) (V+b)
- (d)
PV = 1/3 mnV2
Weight of 112 ml of oxygen at STP on liquefication would be
- (a)
0.32 g
- (b)
0.64 g
- (c)
0.16 g
- (d)
0.96 g
Which one of the following is a postulate of kinetic theory?
- (a)
gases combine in single ratio of their volume
- (b)
The pressure of the gas is due to the hits recorded by the moving molecules on the walls of the container
- (c)
Gases are made of particles called atoms
- (d)
NONE OF THE ABOVE
Which one of the following gases has the greatest rate of diffusion?
- (a)
CO2
- (b)
Cl2
- (c)
NH3
- (d)
O2
Which statement is incorrect about osmotic pressure (P), volume (V) and temperature (T)?
- (a)
\(P\propto 1/V\) (T is constant)
- (b)
\(P\propto T\)(T is constant)
- (c)
\(P\propto V\)(T is constant)
- (d)
PV = constant (T is constant)
A vessel is filled with a mixture of equal masses of oxygen and nitrogen. What is the ratio of partial pressures of oxygen and nitrogen?
- (a)
\({ P }_{ { 0 }_{ 2 } }=0.5\quad { P }_{ { N }_{ 2 } }\)
- (b)
\({ P }_{ { 0 }_{ 2 } }=0.875\quad { P }_{ { N }_{ 2 } }\)
- (c)
\({ P }_{ { 0 }_{ 2 } }= { P }_{ { N }_{ 2 } }\)
- (d)
\({ P }_{ { 0 }_{ 2 } }=1.14\quad { P }_{ { N }_{ 2 } }\)
Substance which can absorb moisture from air without changing its state is called
- (a)
efflorescent
- (b)
deliquescent
- (c)
hygroscopic
- (d)
Monotropic
The phenomenon in which different chemical substances exhibit the same crystalline from is called
- (a)
Isomorphism
- (b)
Polymorphism
- (c)
Enantiotropic
- (d)
Monotropic
The defect produced due to the missing of one positive and one negative ion producing a pair of holes in the crystal lattice is known as
- (a)
Frenkel defect
- (b)
Schottky defect
- (c)
metal excess defect
- (d)
metal deficiency effect
Frenkel defect is produced due to
- (a)
missing of one positive and one negative ion from the crystal lattice
- (b)
displacement of a cation from its proper position to an interstitial lattice site
- (c)
missing of a negative ion from its crystal lattice and the hole being occupied by an electron
- (d)
missing of a positive ion from its crystal lattice and the charge being balanced by adjacent metal ion having two charges instead of one
Which type of crystal should be softest and have the lowest m.ps.
- (a)
moleculer crystals
- (b)
metallic crystals
- (c)
ionic crystals
- (d)
negative crystals
Air is a mixture of N2 and O2 mainly in the ratio of 4 : 1. Five litres of CH4 was burnt in excess of air according to the reaction
\(CH_4+2O_2\rightarrow CO_2+2H_2O\)
The volume of air used during this process would be
- (a)
10 litres
- (b)
20 litres
- (c)
40 litres
- (d)
50 litres
A substance AxBy crystallises in a face centred cubic (FCC) lattice in which atoms A occupy each corner of the cube and atoms B occupy the centres of each face of the cube. Identify the correct composition of the substance AxBy.
- (a)
AB3
- (b)
A4B3
- (c)
A3B
- (d)
Composition cannot be specified
Which of the following defects in the crystals lower its density?
- (a)
Schottky
- (b)
Frenkel
- (c)
Interstitial
- (d)
F-centres
Which one of the following statements in correct?
- (a)
'He' diffuses four times faster than SO2 does
- (b)
'He' diffuses four times faster than CO2 does
- (c)
'He' diffuses four times faster than N2O does
- (d)
'He' diffuses four times faster than ClO2 does
Silicon doped with arsenic is an example of which type of semiconductor?
- (a)
p-type
- (b)
n-type
- (c)
n, p type
- (d)
intrinsic
The edge length of face centred unit cubic cell is 508 pm; if the radius of the cation is 110 pm, the radius of the anion is
- (a)
110 pm
- (b)
144 pm
- (c)
618 pm
- (d)
398 pm
The temperature of 2.0 g of hydrogen was raised from \({ 0 }^{ \circ }C\) to \({ 273 }^{ \circ }C\) at constant pressure. Which of the following statements is correct?
- (a)
the r.m.s. velocity increases by a factor of \(\surd 2\)
- (b)
the mean free path remains constant
- (c)
the average K.E. increases by a factor of 273.
- (d)
the most probable velocity remains unchanged
Six litres of an ideal gas is at STP. The temperature of this gas was first raised to \({ 273 }^{ \circ }C\) at a constant pressure and then the pressure aws changed to 4 atm at constant temperature. The final volume of the gas would be
- (a)
2 L
- (b)
3 L
- (c)
6 L
- (d)
12 L
At \({ 0 }^{ \circ }C,\) the density of a geseous oxide at 2 bar is same as that of nitrogen at 5 bar. The molecular mass of gaseous oxide would be
- (a)
56 g mol-1
- (b)
84 g mol-1
- (c)
28 g mol-1
- (d)
70 g mol-1
A gas is found to have a formula [CO]x. Its vapour density is 70. The value of x is
- (a)
2.5
- (b)
3.0
- (c)
5.0
- (d)
6.0
An open vessel containing air is heated from \({ 27 }^{ \circ }C\) to \({ 127 }^{ \circ }C\). The fraction of air originally present which goes out of it is
- (a)
\(1\over 8\)
- (b)
\(1\over 4\)
- (c)
\(2\over 3\)
- (d)
\(1\over 12\)
A student forgot to add the reaction mixture to the round bottomed flask at \({ 27 }^{ \circ }C\) but put it on the flame. After a lapse of time, he realised his mistake; using a pyrometer he found the temperature of the flask was \({ 477 }^{ \circ }C.\) The fraction of air expelled would be
- (a)
\(1\over 4\)
- (b)
\(2\over 3\)
- (c)
\(1\over 3\)
- (d)
\(3\over 5\)
The compressibility factor for an ideal gas is
- (a)
1.0
- (b)
1.2
- (c)
1.5
- (d)
\(\infty \)