Substance X is a white crystalline solid which melts after 10 seconds on a burner flame. It is soluble in water and insoluble in $$\mathrm{CCl_4}$$ and is a poor conductor of electricity in molten state as well as in aqueous solution. Substance X is

A

an ionic compound

B

a non polar covalent compound

C

a polar covalent compound

D

a pure element