Q47 of 55 Page 61

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): Gases do not liquefy above their critical temperature, even on applying high pressure.


Reason (R): Above critical temperature, the molecular speed is high and intermolecular attractions cannot hold the molecules together because they escape because of high speed.


(i) Both A and R are true and R is the correct explanation of A.


(ii) Both A and R are true but R is not the correct explanation of A.


(iii) A is true but R is false.


(iv)A is false but R is true.


(i)

We know that gases do not liquefy above their critical temperature, even on applying high pressure.


This is because as the temperature reaches above the critical temperature, the speed of the molecule becomes very high due to which the intermolecular attractions is not enough to hold the molecules together and hence they escape because of their high speed.


Now discussing the reason, we observed that the reason is true and is correct explanation of the assertion.


Hence, (i) option is correct.


More from this chapter

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45

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): At constant temperature, pVvs V plot for real gases is not a straight line.


Reason (R): At high pressure all gases have Z > 1 but at intermediate pressure most gases have Z < 1.


(i) Both A and R are true and R is the correct explanation of A.


(ii) Both A and R are true but R is not the correct explanation of A.


(iii) A is true but R is false.


(iv) A is false but R is true.


 46

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): The temperature at which vapour pressure of a liquid is equal to the external pressure is called boiling temperature.


Reason (R): At high altitude atmospheric pressure is high.


(i) Both A and R are true and R is the correct explanation of A.


(ii) Both A and R are true but R is not the correct explanation of A.


(iii) A is true but R is false.


(iv)A is false but R is true.


 48

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): At critical temperature liquid passes into gaseous state imperceptibly and continuously


Reason (R): The density of liquid and gaseous phase is equal to critical temperature.


(i) Both A and R are true and R is the correct explanation of A.


(ii) Both A and R are true but R is not the correct explanation of A.


(iii) A is true but R is false.


(iv) A is false but R is true


 49

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given below each question.

Assertion (A): Liquids tend to have maximum number of molecules at their surface.


Reason (R): Small liquid drops have spherical shape.


(i) Both A and R are true and R is the correct explanation of A.


(ii) Both A and R are true but R is not the correct explanation of A.


(iii) A is true but R is false.


(iv) A is false but R is true.


iv) A is false but R is true.