Galvanising (i.e., zinc coating) of steel sheets is done to________?

Drag co-efficient for flow past immersed body is the ratio of ________ to the product of velocity head and density?

The purpose of providing expansion bellows in the shell of tubular exchanger is to ________?

In producer gas making furnace, steam is added along with air to mainly control the________?

During electrical desalting of crude oil, the electrical conductivity of a mixture of crude oil and water (which ranges between 3 to 8% water) ________ with increase in the amount of water?

If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is________?