*$_Insulation of liquid surface can be achieved by __________ on top of its surface.?

Floating hollow polypropylene spheres

*$_Insulation of liquid surface can be achieved by __________ on top o

1.	*$_Insulation of liquid surface can be achieved by __________ on top of its surface.?
A.	Floating hollow polypropylene spheres
B.	Spraying alumina powder
C.	Putting cement
D.	None of these
Answer» B. Spraying alumina powder