Q109
General ScienceChemistry
Dry ice means
- a.Ice at $-23^{\circ}C$
- b.Ice at $4^{\circ}C$
- c.Solid $SO_2$
- d.Solid $CO_2$
Answer: (D) Solid $CO_2$
Dry ice is solid carbon dioxide. At atmospheric pressure it does not melt but sublimes directly into gas at about $-78.5^{\circ}C$, leaving no liquid - hence 'dry'. It is used as a refrigerant for transporting vaccines, ice cream and frozen food, and for stage fog. Ordinary ice is solid $H_2O$ whatever its temperature; $4^{\circ}C$ is the temperature at which water (a liquid then) has maximum density; solid $SO_2$ has no such use. Other substances that sublime: camphor, naphthalene, iodine, ammonium chloride.