Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

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.

A
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
✓
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: C.

$A$ is true but $R$ is false.

Assertion is correct but reason is wrong. The temperature at which the vapour pressure of a liquid becomes equal to the external pressure is called its boiling point. As the altitude is high, pressure is low.

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MCQ 21 Mark

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.

✓
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
C
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: A.

$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$

According to Andrews, a real gas cannot be liquefied ‘above critical ‘ temperature, whatever pressure is applied. Intermolecular force of gas molecules is low above critical temperature.

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MCQ 31 Mark

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. $44.$
Assertion $(A)$ : Three states of matter are the result of balance between intermolecular forces and thermal energy of the molecules.
Reason $(R)$ : Intermolecular forces tend to keep the molecules together but thermal energy of molecules tends to keep them apart.

✓
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
C
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: A.

$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$

States of matter of a substance depends on the intermolecular force
$\xrightarrow[\text{decrease itermolecular force}]{\text{Solid > liquid > gas}}$
Intermolecular forces keep the molecules together while thermal energy of molecules tends to keep them apart.

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MCQ 41 Mark

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.

✓
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
C
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: A.

$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$

At critical state, surface tension of liquid is zero hence liquid passes into gaseous state imperceptibility and continuously . At this stage, the liquid and vapor phase becomes equal.

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MCQ 51 Mark

Assertion $(A)$ : At constant temperature, $pV$ vs $V$ 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 $Z < 1.$

✓
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
C
$A$ is true but $R$ is false.
D
$A$ and $R$ both are false.

Answer

Correct option: A.

$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$

$PV$ versus $F$ plot is straight line for ideal gases but not for real gases.
At high pressure, there is positive deviation from ideal behavior $(Z < 1)$ but at intermediate or moderate pressure, the real gases pass negative deviation from ideal behavior $(Z < 1).$

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MCQ 61 Mark

Assertion $(A)$ : Liquids tend to have maximum number of molecules at their surface.
Reason $(R)$ : Small liquid drops have spherical shape.

A
$A$ and $R$ both are correct, and $R$ is the correct explanation of $A.$
B
$A$ and $R$ both are correct, but $R$ is not the correct explanation of $A$.
C
$A$ is true but $R$ is false.
✓
$A$ and $R$ both are false.

Answer

Correct option: D.

$A$ and $R$ both are false.

Liquid tends to acquire minimum surface area due to surface tension.
Thus, small liquid drops are spherical. In spherical shape, surface area is minimum.

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Chemistry Assertion (A) & Reason (B) MCQ

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