MCQ Detailed View

Dry ice is the solid form of carbon dioxide (CO₂). Unlike ordinary ice, which is frozen water, dry ice is created when carbon dioxide gas is cooled and compressed until it becomes a solid at around −78.5°C (−109.3°F). It is called “dry” ice because, instead of melting into a liquid as it warms, it sublimates, meaning it directly changes from a solid to a gas without passing through the liquid state.This unique property makes dry ice extremely useful in many applications. It is commonly used as a cooling agent for preserving perishable foods, medical supplies, and biological samples during transportation. Since it does not leave behind liquid water when it warms up, it is especially helpful in situations where moisture is undesirable.

Dry ice also creates a dense fog effect when placed in water because the cold carbon dioxide gas condenses water vapor in the air. This is often used in theatrical productions, concerts, and Halloween displays to produce a smoky or foggy atmosphere safely.

The other options in the question refer to different substances:

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  Methane hydrate is a crystalline solid made of methane and water, found in ocean sediments.

  
  


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  Liquid nitrogen is nitrogen gas cooled to a liquid state at very low temperatures (−196°C).

  
  


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  Frozen water is simply ice made from water, not carbon dioxide.

  
  

Because of its extreme cold, dry ice must be handled with care. Direct contact can cause frostbite or burns, and it should only be used in well-ventilated spaces, as sublimating carbon dioxide can displace oxygen in the air.

This question falls under Chemistry because it involves understanding the states of matter, properties of gases, phase changes, and compounds like carbon dioxide, which are fundamental concepts in the study of physical and inorganic chemistry.