Four substances have the physical properties shown.
Which substance is an ionic solid?
melting point
1 °C
boiling point
1°C
electrical
conductivity
of solid
electrical
conductivity
of molten
substance
electrical
conductivity
of aqueous
solution
A
-115
-85
poor
poor
good
B
660
2470
good
good
insoluble
с
993
1695
poor
good
good
D
1610
2230
poor
poor
insoluble