Pick out the wrong statement?

Solvent used for dewaxing of petroleum products are________?

Main constituent of cotton fiber is ________?

For storing hazardous chemicals in large storage tanks, the minimum safe distance between the two tanks should range between ________ times the tank diameter?

A good metallurgical coke should have very low________?

Boundary layer thickness in laminar flow over a flat plate increases as(where, d = distance from the leading edge.)?