States of Matter is one of the core topics of JEE Main chemistry syllabus. Usually, the topic has 1-3 questions covering a weightage of 4-12% in JEE Main question paper. Having thoroughly practised the subtopics will help students crack the section well.
Some of the important subtopics from States of Matter include Properties of Gases, Gas Laws, Dalton’s Law for partial pressure, Ideal gas equation, Kinetic theory of gas, Concept of root mean square, Properties of liquid, Classification of solids, Unit cell and lattices, Voids, Electrical and magnetic properties, etc. Check JEE Main Chemistry Syllabus
Questions asked from States of Matter topic are usually direct in nature The difficulty level of States of Matter in JEE Main exam is moderate. The table below shows the weightage of the topic in the last five years:9
Year of an Exam | Weightage (%) |
---|---|
2020 | 6.6 % (2 Questions) |
2019 | 6.6 % (2 Questions) |
2018 | 3 to 5 % (1-2 Questions) |
2017 | 3% (1 Question) |
2016 | 9.9 %(3 Questions) |
Check JEE Main Chemistry Preparation
Ques. The molecular velocity of any gas is …..
Solution : (D)
According to the law of gas “The Molecular velocity of any gas is directly proportional to the square root of the temperature ”.
Ques. The temperature at which oxygen molecules have the same root mean square
speed as helium atoms have at 300 K is:
(Atomic masses : He = 4 u, O = 16 u)
Solution: (D)
Given Atomic masses : He = 4 u, O = 16 u
(Vrms) O2 = (Vrms) He
sqrt(3RT1/M1) = sqrt(3RT2/M2)
T1 /M1 = T2/M2
T1/32 = 300/4
T1 = 300×32/4
= 2400 K
Ques. Value of gas constant R is….
Solution: (C)
R = 8.3 J mol-1 K-1
Ques Which one of the following is the wrong assumption of the kinetic theory of gases?
Solution: (A)
The molecules are always in random motion and obey Newton’s law of motion. They have velocities in all directions ranging from zero to infinity.
Ques. A pressure cooker reduces cooking time for food because…
Solution: (B)
By Gay Lussac’s law, at a constant pressure of a given mass of a gas is directly proportional to the absolute temperature of the gas. So on increasing pressure, temperature also increases. So the boiling point of water is also increased.
Ques. ‘a’ and ‘b’ are Vander Waal’s constants for gases. Chlorine is more easily liquified than ethane because:
Solution: (B)
Greater the ‘a’ value, more easily the gas is liquified, lower the ‘b’ value, more easily the gas is liquified.
Ques. In Van der Waals equation of state of the gas law, the constant ‘b’ is a measure of
Solution: (C)
In Van der Waals equation, ‘b’ is the excluded volume. Excluded volume is the volume occupied by the molecules of gas
Ques. Which intermolecular force is most responsible in allowing xenon gas to liquefy?
Solution: (A)
For the liquefaction of xenon, instantaneous dipole induced dipole forces are responsible.
Ques. The compressibility factor for a real gas at high pressure is :
Solution: (D)
(P+a/V2)(V-b) = RT [Real gas equation]
a/V2 can be neglected at high pressure.
PV-Pb = RT
PV/RT = (RT/RT) + (Pb/RT)
PV/RT = 1 + (Pb/RT) …(1)
Z = PV/RT …(2)
Equating (1) and (2)
Z = 1 + (Pb/RT)
While preparing for any examinations “Quick Formulas” are very important for last-minute exam preparation. Here some formulas for JEE Main States of Matter.
P1V1 = P2V2 (at constant T and n)
V1/T1=V2/T2(at Constant P and n)
V = kn (at constant P and T)
PV=nRT
P1V1/T1=P2V2/T2
PTotal = P1 + P2 + P3 + …Pn
Z=PV/RT
Umps=sqrt(2KT/M)
Characteristics | Solid State | Liquid State | Gas State |
---|---|---|---|
Shape | Fixed | Indefinite | Indefinite |
Volume | Fixed | Fixed | Indefinite |
Forces Applied | Strong | weak | Almost Zero |
Motion of Particles | Restricted | Very slow | random |
Packing of Particles | Closely packed | Less closely packed | Very loosely packed |
Compressibility | Incompressible | Compressible | Highly Compressible |
Density | High | Low | Very Low |
Check JEE Main Study Notes on States of Matter
*The article might have information for the previous academic years, please refer the official website of the exam.