The area of double pipe heat exchanger should be

A. Frog B. Mould Board C. Land Side D. None of these

A. Depth of bed B. Porosity of the bed C. Density of the particles D. All of the above

A. To carry the seeds and fertiliser in separate compartments B. To open furrows at uniform depth C. To cover the seed and fertiliser D. All of the above

A. Zero B. Positive slip C. Negative slip D. None of these