A two stage compressor is used to compress an ideal gas. The gas is cooled to the initial temperature after each stage. The intermediate pressure for the minimum total work requirement should be equal to the __________ mean of P₁ and P₂. (where, P₁ and P₂ are initial and final pressures respectively)

Sublimation temperature of dry ice (solid CO₂) is __________ °C.

The equation relating E, P, V and T which is true for all substanes under all conditions is given by $${\left( {\frac{{\partial {\text{E}}}}{{\partial {\text{V}}}}} \right)_{\text{T}}} = {\text{T}} \cdot {\left( {\frac{{\partial {\text{P}}}}{{\partial {\text{T}}}}} \right)_{\text{H}}} - {\text{P}}{\text{.}}$$      This equation is called the

Henry's law is closely obeyed by a gas, when its __________ is extremely high.

If an ideal solution is formed by mixing two pure liquids in any proportion, then the __________ of mixing is zero.