Yes, crows are vicious.
A congress of crows, or a murder of crows.
A number of crows is called a "murder" of crows.
Molten salt is viscous.
A group of crows is called a murder.
By viscous, I think you mean viscosity. Viscous is a adjective referring to the thickness of a substance; therefore, yes, ketchup is somewhat viscous.
crows migrate in winter and summer
Hover, Muster, Parcel, Murder A Hover of Crows A Murder of Crows A Muster of Crows
crows turn me on.
other crows
Crows. (a murder of crows).
The Crows ended in 1955.
The Crows was created in 1951.