One mole of a non-ideal gas undergoes a change of state (2.0 atm, 3.0 L, 95 K)$\to$(4.0 atm, 5.0 L, 245 K) with a change in internal energy, $∆$U = 30.0 L atm. The change in enthalpy ($∆$H) of the process in L atm is:

1. 40.0

2. 42.3

3. 44.0

4. not defined, because pressure is not constant

In a flask, colourless N₂O₄(g) is in equilibrium with brown coloured NO₂(g). At equilibrium when the flask is heated to 100$°$C, the brown colour deepens and on cooling it becomes less coloured. Which statement is incorrect about this observation?

1. The $∆$H for the reaction N₂O₄(g)$\rightleftharpoons$ 2NO₂(g) is +ve

2. Paramagnetism increases on heating

3. The $∆$H-$∆$U at 100$°$C is equal to 200 cal

4. Dimerisation is reduced on heating

When an ideal gas is compressed adiabatically and reversibly, the final temperature is:

1. higher than the initial temperature

2. lower than the initial temperature

3. the same as the initial temperature

4. dependent on the rate of compression

1 liter-atmosphere is equal to:

1. 101.3 J                           

2. 24.20 cal

3. 101.3 x 10⁷ erg               

4. All of the above

An ideal gas expands at a constant external pressure of 2.0 atmosphere by 20 litre and absorbs 10kJ of heat from surrounding. What is the change in internal energy of the system:-

(1) 4052 J

(2) 5948 J

(3) 14052 J

(4) 9940 J

36 ml of pure water takes 100 sec to evaporate from a vessel and heater connected to an electric source which delivers 806 watt. The $∆{\mathrm{H}}_{\mathrm{vaporisation}}$ of H₂O is:-

(1) 40.3 kJ/mol

(2) 43.2 kJ/mol

(3) 4.03 kJ/mol

(4) None of these

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5 atm from an initial volume of 2.50 L to a final volume of 4.50 L. The change in internal energy $∆$U of the gas in joules will be

(1) 1136.25 J

(2) - 500 J

(3) - 505 J

(4) + 515 J

The first law of thermodynamics is a statement of:

1. Conservation of mass

2. Conservation of linear momentum

3. Conservation of energy

4. Conservation of angular momentum

A mixture of two moles of carbon monoxide and one mole of oxygen, in a closed vessel is ignited to convert the carbon monoxide to carbon dioxide. If ΔH is the enthalpy change and ΔE is the change in internal energy, then

(1) ΔH > ΔE

(2) ΔH < ΔE

(3) ΔH = ΔE

(4) The relationship depends on the capacity of the vessel

If ΔH is the change in enthalpy and ΔE the change in internal energy accompanying a gaseous reaction

(1) ΔH is always greater than ΔE

(2) ΔH < ΔE only if the number of moles of the products is greater than the number of the reactants

(3) ΔH is always less than ΔE

(4) ΔH < ΔE only if the number of moles of the products is less than the number of moles of the reactants