Question

Statement 1: At STP, 22.4Liters of He will have the same volume as one mole of ${H_2}$ (assume ideal gases).
Statement II: One mole or 22.4Liters of any gas STP will have the same mass.
A.True, false
B.False, true
C.True, True, correct explanation
D.True, true, not correct explanation

Answer 1

Hint: At standard conditions, we have to know that volumes and moles of gases are given by Avogadro’s gas laws. It states that the total number of molecules (or) atoms present in a gas is directly proportional to the occupied volume of the gas under constant pressure and temperature. For a gas, it relates the pressure, temperature, volume and quantity of a substance.

Complete step by step answer:
Statement I is true because according to Avogadro’s law under similar conditions of temperature and pressure, equal volumes of various gases have the same number of molecules. This relationship could be obtained from kinetic theory of gases under the consideration of a perfect ideal gas. This law is valid for real gas at high temperatures and low pressures.
Avogadro’s Law:
At constant pressure and temperature, the number of moles in the gas and the volume of the gas are proportionally related.
$\dfrac{V}{n} = K$
Where,
V represents the volume of the gas.
T represents the temperature of the gas in Kelvin.
K represents the constant.
P represents the pressure of the gas.
n represents the number of moles.
According to Avogadro’s law, the ratio of volume and amount of gaseous substance is fixed at constant pressure and temperature. The value of this constant (k) could be obtained as:
$k = \dfrac{{RT}}{P}$
Under standard conditions for temperature and pressure, the value of T is \[273.15K\] and the value of P corresponds to \[101.325kPa\]. Therefore, we can give the volume occupied by one mole of a gas at STP is:
Volume occupied by 1 mole of gas = \[\dfrac{{\left( {8.314{\text{ }}J.mo{l^{ - 1}}.{K^{ - 1}}} \right) \times \left( {273.15{\text{ }}K} \right)}}{{101.325kPa}} = {\text{ }}22.4{\text{ }}litres\]
Therefore, at standard pressure and temperature, one mole of any gaseous substance occupies 22.4 liters of volume.
Statement II is false because at standard pressure and temperature, all gaseous molecules contain equal volume for one mole of gas and that volume is always equal to 22.4Liters.
Thus, Statement I is true statement and statement II is false statement.
Therefore, the option (A) is correct.

Note: The amounts of gas are compared at a set of standard conditions of temperature and pressure, abbreviated as STP. At STP, one mole of any gas has the same volume \[22.4L\] called the standard molar volume.
Example:
Under STP conditions, one mole of nitrogen gas and one mole of helium gas each contain \[{\text{6}}{\text{.02 \times 1}}{{\text{0}}^{{\text{23}}}}{\text{ }}\] particles of gas and occupy a volume of \[22.4L\]at ${{\text{0}}^{\text{o}}}C$ and $1atm$ pressure. Since the molar masses of nitrogen and helium are different (\[{\text{28}}{\text{.02g}}\] for \[{N_2}\] compared to \[4.003g\] for\[He\]) one mole of each substance has a different mass.