Which one of the following is also known as Dry ice in its solid form?

CONCEPT:

Dry Ice

• Dry ice is the solid form of carbon dioxide (CO₂).
• It is called "dry ice" because it does not melt into a liquid when heated but instead sublimates directly into carbon dioxide gas.
• This property makes it useful for cooling purposes, especially where the presence of water is undesirable.
• Dry ice is extremely cold, with a temperature of approximately -78.5°C (-109.3°F).

EXPLANATION:

• The question asks which compound is known as "dry ice" in its solid form.
• SiO₂ (Option 1) is silicon dioxide, commonly known as sand or quartz.
• CO₂ (Option 2) is carbon dioxide, which is dry ice in its solid form.
• CaO (Option 3) is calcium oxide, commonly known as quicklime.
• MgO (Option 4) is magnesium oxide, a compound used in refractory applications.

Therefore, dry ice in its solid form is carbon dioxide (CO₂).