Question 1

In van der Waal's equation of state for a nonideal gas, the term that accounts for intermolecular forces is

Accepted Answer

(P+ a V^2 )(V-b)=R T; Here (P+ a V^2 ) represents the intermolecular forces.

Question 2

Kinetic theory of gases proves

Accepted Answer

Kinetic theory of gases proves all the given gas laws.

Question 3

How will raise in temperature affects the viscosity of liquids and gases?

Accepted Answer

In case of liquids, cohesive forces decrease and hence, their viscosity decreases while increasing the temperature. However, in case of gases, with the increase in temperature kinetic energy of gaseous molecules increases and the molecules become more mobile.

Question 4

The given graph represents the variation of compressibility factor (Z)= p V n R T , for three real gases A, B and C. Identify the only incorrect statement.

Accepted Answer

From the graph it is clear that, the value of ' Z ' decreases with increase of pressure. We can explain as follows on the basis of van der Waals' equation. At high pressure, when ' p ' is large, V will be small and one cannot ignore ' b ' in comparison to V. However, the team a / V^2 may be considered negligible in comparison to ' p ' in van der Waals' equation. (p+ a V^2 )(V-b)=n R T p(V-b)=n R T p V-p b=n R T or p V n R T =1+ p b n R T or Z=1+ p b n R T Thus, Z is greater than 1. As pressure i

Question 5

Two vessels of volumes 16.4 ~L and 5 ~L contain two ideal gases of molecular existence at the respective temperature of 27^ C and 227^ C and exert 1.5 and 4.1 atmospheres respectively. The ratio of th

Accepted Answer

Given conditions V _ 1 =16.4 ~L , ~V _ 2 =5 ~L P _ 1 =1.5 ~atm , P _ 2 =4.1 ~atm T _ 1 =273+27=300 ~K T _ 2 =273+227=500 ~K Applying gas equation, P _ 1 ~V _ 1 P _ 2 ~V _ 2 = n _ 1 ~T _ 1 n _ 2 ~T _ 2 n _ 1 n _ 2 = P _ 1 ~V _ 1 ~T _ 1 P _ 2 ~V _ 2 ~T _ 2 1.5 16.4 500 4.1 5 300 = 2 1

States of Matter — Previous Year Questions & Solutions