Rhombic sulphur on heating in a test tube or flask

Options

A. sublimes
B. melts to a thin pale yellow liquid and then vaporises
C. melts to a thin dark coloured liquid and then vaporises
D. None of these

Answer

D

Explanation

Rhombic sulphur on heating in a test tube or a flask (in an open vessel like china dish, it will bum) first melts to a clear yellow mobile liquid at 387.5 K. When heated further, the liquid, gradually darkens in colour (dark red). At 453 K the liquid suddenly becomes very viscous. If heating is continued, the viscosity decreases once again, but the colour remains dark. Finally at 717 K the liquid boils to give reddish brown vapour of `S_2`.