For a reaction to be spontaneous at all temperatures :

• ΔG and ΔH should be negative

• ΔG and ΔH should be positive

• ΔG =ΔS = 0

• ΔH< ΔG

For a reversible reaction:

$\mathrm{X}\left(\mathrm{g}\right) + 3\mathrm{Y} \left(\mathrm{g}\right) \rightleftharpoons 2\mathrm{Z} \left(\mathrm{g}\right) ; ∆\mathrm{H} = -40\mathrm{kJ}$, the standard entropies of X, Y and Z are 60, 40 and 50 JK^-1 mol^-1 respectively. The temperature at which the above reaction attains equilibrium is about :

• 400 K

• 500 K

• 273 K

• 373 K

Which of the following is an intensive property?

• temperature

• viscosity

• surface tension

• all of these

In equilibrium state the value of $∆$G is

• zero

• negative

• positive

• may be negative or positive

One mole of which of the following has the highest entropy?

• Liquid nitrogen

• Hydrogen gas

• Mercury

• Diamond

Entropy of the universe is

• constant

• zero

• continuously decreasing

• continuously increasing

497.

The relation between $∆$H and $∆$U is

• $∆\mathrm{H} = ∆\mathrm{U} + \mathrm{RT}$

• $∆\mathrm{H} = ∆\mathrm{U} - ∆\mathrm{nRT}$

• $∆\mathrm{H} = ∆\mathrm{U} + ∆\mathrm{nRT}$

• $∆\mathrm{U} = ∆\mathrm{H} + ∆\mathrm{nRT}$

In which of the following process, maximum increase in entropy is observed?

• Melting of ice

• Sublimation of napthalene

• Condenstaion of water

• Dissolution of salt in water

Considering the reaction C (s) + O₂ (g) → CO₂ (g) + 393.5 kJ the signs of $∆$H, $∆$S and $∆$G respectively are

• +, -, -

• -, +, +

• -, -, -

• -, +, -

If one mole of ammonia and one mole of hydrogen chloride are mixed in a closed container to form ammonium chloride gas, then

• ΔH > ΔU

• ΔH = ΔU

• ΔH < ΔU

• there is no relationship