Question

Assertion: The volume of 1 mole of an ideal gas at 1 bar pressure at $\text{25}{}^\circ \text{C}$ is 24.78 litre.
Reason: 1 bar = 0.987 atm.
(A) Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
(B) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
(C) Assertion is correct but Reason is incorrect.
(D) Both Assertion and Reason are incorrect.

Answer 1

Hint: Pressure and volume are always directly proportional to the gas constant as well as to the temperature. A bar is a unit of pressure and it differs for different units such as atm, kPa, Ba, etc. and has a fixed value for each unit.
Complete step by step answer:
-To find out the correct answer we will calculate the given parameters of Assertion by the formula Ideal Gas Formula.
-The formula of Ideal Gas is PV = nRT, the value of pressure, no. of moles, Gas constant and temperature is given in the question.
-So, by putting all the values in the formula we will get,
$\begin{align}
  & V\text{= }\dfrac{nRT}{P} \\
 & V\text{= }\dfrac{\text{1 }\cdot \text{ 0}\text{.0821 }\cdot \text{ 298}}{0.987} \\
 & V=\text{ 24}\text{.78 litre } \\
\end{align}$
-So, the given value of volume in the question is correct, that is 24.78 litre.
-Also, we know that the value of 1 bar is 0.987 atm but it is not the explanation of the assertion.
-The given reason is just a part of a solution and not the explanation.
Therefore, option (B) is correct that is both assertion and reason are correct but the reason is not the correct explanation for the assertion.
 Note: The value of 1 bar is 0.987 in standard atmosphere, 100000 Pascal and 750 Torr. The value of temperature is always taken in the Kelvin. One should do all the calculations twice to get the correct result.