Chemistry NCERT Exemplar Solutions Class 11th Chapter Five

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The assumption of kinetic theory of gases that there is no force of attraction between the molecules of a gas is applicable for real gases. The evidence for this is  that the real gas can be liquified at high pressure and low temperature. This proves that there is force of attraction between the molecules of gas.

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The two intermolecular forces that exist between HF molecules in liquid state are hydrogen bonding (as F is a highly electronegative atom) and  dipole-dipole interaction (as HF is a polar molecule).

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The energy which arises due to motion of atoms or molecules in a body is known as thermal energy and the average kinetic energies of all the molecules increases with increases in temperature.

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Water and alcohol are polar  molecules which have high electronegative O atm  so they  have hydrogen bonding along with dipole-dipole interaction.   Hexane is a nonpolar molecule that has London dispersion force  which is a weak force between the molecules. Water has stronger H-bonding than alcohol. So, the order of attractive force will be:

Hexane  <   Alcohol  <  Water

More attractive forces between the molecules, the greater the  magnitude of surface tension of the liquid.

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The assumption of the kinetic theory of gases which states that- “ there is no force of attraction between the molecules of a gas. ” is a correct statement. Ideal gas has minimum force of attraction between the molecules and hence, it cannot be liquified. Liquefaction of a gas can only  be done when the force of attraction between the molecules increases, which is not possible for an ideal gas.

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Unit of R depends on the  units of  p, V and T are measured, We know,   R=pVnT  Now, let's say, the  pressure is measured in Pascal, per mole volume is measured in m³ and temperature is measured in Kelvin,   then. Units of 'R' are Pa m³K^-1 mol^-1. Also, R is work done per mole per kelvin. It's unit is J K^-1 mol^-1 (Joule is the unit of work done).

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On increasing the pressure slightly the gas 'A' liquefies but gas B does not liquify even on applying high pressure until it is cooled at same  conditions of temperature and pressure  filled in equal capacity containers it happens because the gas 'A' being at the  critical temperature liquifies on slightly increasing the pressure and  gas 'B' being at higher temperature than critical temperature does not liquifies even on applying high pressure until it is cooled.

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A gas that  follows Boyle's law, Charle's law and Avogadro's law is called an ideal gas.

Real gas behaves ideal under low pressure and high temperature. Under these conditions, the intermolecular interactions are minimum.

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The molar volume of both nitrogen and argon at 273.15 K and 1 atm is 22.4 L.

At STP (1 atm pressure and 273.15 K or 0⁰ C), the molar volume i.e the volume of 1 mole gas is 22.4L.