The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost are P. Inlet pressure Q. Compressor rpm R. Delivery pressure S. Volumetric flow rate at inlet.

A. Thermal conductivity B. Electrical conductivity C. Specific gravity D. Electrical resistivity

A. $$\frac{{\text{V}}}{{{{\text{V}}_{\max }}}} = {\left( {\frac{{\text{x}}}{{\text{r}}}} \right)^{\frac{1}{7}}}$$ B. $$\frac{{\text{V}}}{{{{\text{V}}_{\max }}}} = {\left( {\frac{{\text{r}}}{{\text{x}}}} \right)^{\frac{1}{7}}}$$ C. $$\frac{{\text{V}}}{{{{\text{V}}_{\max }}}} = {\left( {{\text{x}} \times {\text{r}}} \right)^{\frac{1}{7}}}$$ D. None of these

A. d B. $$\frac{1}{{\text{d}}}$$ C. $$\sigma $$ D. $$\frac{l}{\sigma }$$

A. $$\frac{{4\pi {\text{g}}}}{3}$$ B. $$\frac{{0.01\pi {\text{gH}}}}{4}$$ C. $$\frac{{0.01\pi {\text{gH}}}}{8}$$ D. $$\frac{{0.04\pi {\text{gH}}}}{3}$$